Greatness is contagious. So says the advertising campaign for this World Cup. What does a society do in the event of a contagious outbreak? It isolates those in danger of infection. Tells its weakest members to stay at home. That is what cricket will do at future World Cups.

Fourteen teams will contest the event in Australia and New Zealand this year. In England in 2019 it will be ten teams. The most vulnerable members of the cricket family will have little chance of catching greatness then. Let's hope they contract a dose of it here.

In contemplating the next six weeks of cricket, the Associates might seem a peculiar place to start, but then, they have always been the most curious feature of cricket's showpiece event. Who doesn't look at records of the 1975 tournament and marvel at the presence of a team called East Africa? Associates don't win the World Cup, but they win a lot of friends.

Outside of finals and semi-finals, what are the most vivid World Cup memories for the average fan? Watching Ireland's Kevin O'Brien destroy England in 2011. Seeing floppy-hatted UAE captain Sultan Zarawani face Allan Donald in 1996. Witnessing John Davison's 67-ball hundred for Canada against West Indies in 2003. Seeing Bermuda's Dwayne Leverock take a diving catch in 2007. Watching Ireland beat Pakistan in 2007, Zimbabwe topple Australia in 1983, Kenya reach the semi-finals in 2003.

Kevin O'Brien is a new Irish hero after his stunning century overcame England Getty Images

These are the brilliant punctuation marks in the otherwise longwinded sentence that is a cricket World Cup. By cutting back the number of teams, weeks could be shaved off the tournament. But last month the ICC approved the dates for the ten-team 2019 World Cup: May 30 to July 15. That's three days longer than this year's six-week, 14-side event.

If 2014 will go down as the year the "Big Three" took over world cricket, 2015 might be remembered as the year the Associates were squeezed out. The ICC has created a pathway to Test cricket for the leading Associates, but the World Cup's future suggests the game is becoming less inclusive. As Ireland's Ed Joyce put it last week: "We seem to be the only sport that has a World Cup that is contracting rather than expanding."

Afghanistan's sudden emergence is not only one of the most remarkable stories in cricket, but in all of world sport. A nation ravaged by wars and insurgency, a country that before 2001 was not even an Affiliate ICC member is now playing at the World Cup. Had Americans any interest in cricket, an Oscar-winning dramatisation of their journey would have been made by now.

Ireland have been the great success story of the past two World Cups. They might qualify for the next one, but would likely have to finish in the top two of a qualifying event in Bangladesh. In which Bangladesh will almost certainly be playing as well. The teams that succeed on Bangladesh's turning pitches will earn a place at a World Cup in conditions that will swing. Talk about setting teams up for failure.

There is every chance that Bangladesh and Zimbabwe will qualify and the 2019 World Cup will feature only the ten Test-playing nations. Instead, the World T20 looms as the future showcase for most Associates. Ireland are the Associate with the most potential for Test promotion soon but, if a team gears itself towards the 20-over game, its long-form hopes must recede.

So let's enjoy the Associates while we can, let's hope 2015 provides more great memories from the teams disparaged as "minnows". This year, from beyond the Test world, we will see Scotland and UAE as well as Ireland and Afghanistan. Will they make up the numbers, or numb the makers of cricket's new world order?

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The Big Three. Australia, England, India. The hosts (or co-hosts) of the next three World Cups. Last time a World Cup was won by anyone other than Australia or India was 1996, when a former Associate nation proved that from little things, big things can grow. Sri Lanka had been given opportunities, had evolved into an ICC Full Member, and had triumphed. Then came a decade of Australian greatness that was not contagious.

Australia will enter this year's tournament as favourites, injury concerns around their captain Michael Clarke and star finisher James Faulkner notwithstanding. They have lost only two of their past 20 ODIs at home, one to South Africa and one to England, both at the WACA. Their only Perth match in this World Cup is against Afghanistan, although a trip to Auckland is required for a match against New Zealand.

"India have not won a match on tour, and only one of their past 13 ODIs in Australia and New Zealand. They must also be physically and mentally drained after a non-stop year of playing"

The conditions will make Australia, South Africa and New Zealand hard to beat; it is notable that Australia may eschew a specialist spinner, instead relying on Glenn Maxwell. At the 2011 World Cup in Asia, 43% of wickets fell to spin. In New Zealand this summer, spin has claimed only 21% of ODI wickets, and only 17% in Australia this season. The lack of bite off the pitch will gnaw at the reigning champions.

India have not won a match on their tour of Australia this summer, and only one of their past 13 ODIs in Australia and New Zealand. They must also be physically and mentally drained after a more-or-less non-stop year of playing. MS Dhoni's wife gave birth last Friday, but who knows when he will meet his daughter. India have the batting to threaten, but their bowling looks tepid on these pitches.

The other member of the Big Three, England, enter the tournament with a surprisingly settled side, given they changed captains seven weeks ago. Not exactly renowned for their ODI exploits, England have not made a World Cup final - or semi-final, for that matter - since the last time it was held in this part of the world, in 1992. They are not among the favourites but could be the tournament's slow burners.

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On a quiet Tuesday afternoon early last October, a group of men in black stood outside the MCG change-rooms and stared out over the ground. It looked more like a beach cricket venue than the site of a World Cup final, the turf having been ripped up after the AFL season and yet to be relaid over the sandy-looking surface. These men didn't care; they were there to soak up the vibe of the place.

This was a reconnaissance mission for the New Zealand cricket team. They were visualising the day, nearly six months ahead, when they hoped to be back at the giant stadium contesting the World Cup final. New Zealand will play every game at home until the decider, should they make it. Many of their players had never been to the MCG; better to introduce them with a low-key visit than see it for the first time in the last week of March.

The event spoke of a quiet confidence in the New Zealand camp, and why not? They have reached six World Cup semi-finals, sharing the record with Australia and Pakistan. New Zealand, though, have lost them all. This might be their best chance of going all the way, with their home advantage and batting power, led by Brendon McCullum and Kane Williamson.

Kane Williamson and Grant Elliott added 59 for the fourth wicket Getty Images

Another team from below the equator and outside the Big Three will quietly go about their business in Pool B. It is the pool that features neither of the host nations, but South Africa's real job will begin in the quarter-finals. A team that has never won a World Cup knockout match, South Africa will rarely have a better chance - the conditions are like home, without the expectations that fall upon hosts.

They did lose 4-1 to Australia in November, but their balance was awry with JP Duminy injured. A full-strength South Africa is a well-weighted outfit boasting the top two one-day batsmen in the world - AB de Villiers and Hashim Amla - as well as two of the top 10 bowlers. Under de Villiers, this seems like a team with belief, but will that confidence carry into the knockout stages?

If South Africa have underachieved at World Cups, Sri Lanka certainly have not. Winners in 1996 and runners-up at the past two tournaments, Sri Lanka have arguably the best chance of any of the Asian teams this time. Although they lost 4-2 in New Zealand this summer, their last two ODI series in Australia have resulted in a 2-2 draw and forcing Australia to a third final in a tri-series.

The experience of their batsmen - Kumar Sangakkara, Mahela Jayawardene and Tillakaratne Dilshan - and the presence of match-winning fast bowlers Lasith Malinga and Nuwan Kulasekara makes them a serious contender. Farewelling Sangakkara and Jayawardene with a World Cup triumph to add to their World T20 title from last year would be fitting.

An Asian team did indeed raise the trophy last time the World Cup was played in this part of the world, but it would take something unexpected for Pakistan to repeat the effort in 2015. Last time they played in Australia they lost 5-0, and this summer lost 2-0 in New Zealand. They are also without the No. 1 ODI bowler in the world, Saeed Ajmal, although his action has been deemed legal and he may yet join the squad.

Pakistan are in the same pool as West Indies, who would need to overcome internal squabbles and poor form to get anywhere. Dwayne Bravo and Kieron Pollard were not picked, the No. 2 ODI bowler in the world, Sunil Narine, withdrew due to concerns over his action, and there is a new, raw captain, Jason Holder. Of the top eight teams, West Indies are in most danger of going home early.

Bangladesh and Zimbabwe round out the Full Members, and it is hard to see either playing a major role. In the backs of their minds, they might even wonder what the future holds for them at World Cups, with the likelihood they will need to qualify for the next tournament by outplaying the Associates. The bottom of the top ten might soon become a dangerous place.

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The Bangladesh players train at the SCG BCB

Much might change in the next four years; plenty certainly has in the past four. In the 3099 one-day internationals played before the 2011 World Cup, only once had a batsman scored a double-century - Sachin Tendulkar's 200 not out against South Africa in Gwalior in 2010. It has happened three times since the last World Cup, most recently Rohit Sharma's 264 in Kolkata in November.

All of ODI cricket's double-centuries have occurred in India, but even in Australia and New Zealand it is still a good time to be a batsman in one-day internationals. Since the 2011 World Cup, the ICC has changed the rules to allow no more than four fielders outside the circle at any one time, instead of five. A new ball is now used from each end during an innings.

In these conditions, that may help bowlers to have impact but it also means balls stay hard and fly off the bat throughout the innings, and usually find the big gaps in the outfield. David Richardson, the ICC chief executive, said last week that the size of bats was a worry, and that boundaries will be pushed back where possible during this World Cup.

The two fastest hundreds in ODI history have both occurred in the past 14 months, and both in the southern hemisphere. West Indies were on the receiving end of both, when Corey Anderson blasted a 36-ball ton in Queenstown last January, and then when AB de Villiers went five balls better in an audacious, gobsmacking display in Johannesburg last month.

It's a challenging time to be a one-day bowler, and those who fare best in this World Cup will be those who can swing the white ball with the kind of control displayed by Mitchell Starc during the recent tri-series in Australia. Wasim Akram was the leading wicket taker in the 1992 World Cup in this part of the world; the game might have changed, but down under, swing is still king.

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It is so long since the last World Cup in Australia and New Zealand - 23 years - that many of the current players can't remember it, or weren't born. Daniel Vettori remembers. He was a teenager when his country was gripped by World Cup fever. He vividly recalls watching Martin Crowe score a hundred as New Zealand beat Australia in the tournament opener in Auckland.

"I have very fond memories," Vettori told ESPNcricinfo last year. "The format really appealed back then. We played all the teams."

Floodlights were used for the first time in a World Cup Getty Images

Not so this time. The format of this World Cup - two pools of seven teams, and the top four from each pool progressing to quarter-finals - is designed to reduce the chances of the major sides bombing out early. An Associate, or Bangladesh or Zimbabwe, would need a sustained run of strong form to get through, rather than one good day.

There will be games whose only point is the man fielding forward of gully. Every fixture in that 1992 World Cup meant something, because teams were jostling for four semi-final spots from the beginning. In 1992 there were 39 matches in the whole tournament; this time it's 42 before the knockout phase even begins. Deleting the quarter-finals could have ensured every pool match was meaningful.

But then again, in 1992 the World Cup was sponsored by a cigarette company and only one game featured 300-plus totals. There was no DRS, and infamously no Duckworth-Lewis. The sport, like society, has moved on. The highest-scoring clash was Zimbabwe v Sri Lanka at the tiny New Plymouth ground, one of many smaller towns and cities that hosted World Cup matches that year.

This time, there will be no diversion to Ballarat, or Mackay, just the main venues in both countries. There is still a good news story among them. Christchurch was left wondering after its 2011 earthquake whether it would play any role in this World Cup. Lancaster Park is closed, but the newly redeveloped Hagley Oval will not only host World Cup games, but also the opening ceremony and first match.

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Greatness is contagious: World Cup 2015 ad campaign Devashish Fuloria/ESPNcricinfo

There is one other notable difference from 1992: four Associates are present. Back then, Zimbabwe was the only non-Test nation in the tournament, although they were granted Test status later that year. Like Sri Lanka before them and Bangladesh after them, they had progressed from World Cup "minnow" to Test competitor. What, then, for Ireland, Afghanistan, Scotland and the UAE?

There will be those who view the meandering first month of the World Cup as proof that format change is necessary. As evidence, they will point to the fact that tickets for this Sunday's India-Pakistan match at Adelaide Oval sold out within 20 minutes of becoming available. It may well become the most-watched match in the history of cricket, given the ICC's broadcasting reach.

Imagine the missed (financial) opportunities if India and Pakistan had ended up in different pools. Instead, imagine a World Cup in which only ten teams play, and everyone plays everyone. That means everyone plays India, and that in turn means money, money, money. In 2019, there will be no need to imagine - it will be a reality.

This World Cup culminates in the last week in March, but it is about so much more. It is the last chance for 50-over cricket to be truly inclusive, and broad-minded. Let's hope the next six weeks bring a few special moments, and surprises. Let's hope that greatness truly does become contagious.