When 29-year-old Peter Edgar returned to Belfast in 2009 after a year's work experience in the U.S., he saw Northern Ireland through new eyes. There were opportunities everywhere.

"What my year abroad taught me was how to connect with people so as to create ventures and opportunities for others," he said in an interview last week. He now works at Catalyst Inc., a Belfast-based not-for-profit that seeks out inventors across Northern Ireland to incubate and monetize their ideas on domestic and international markets.

Edgar was 10 when the 30-year civil conflict in Northern Ireland, known as the "Troubles," ended.

In a nod to the Good Friday Agreement that ended the conflict in 1998, people Edgar's age and younger are referred to as the "Good Friday Generation," meaning they grew up freer and less hindered by violence and sectarianism.

A former customs guard hut on the north-south Irish border stands disused as Brexit is triggered on March 29 in Newry, Northern Ireland. It will likely be revived in two years, when the U.K. exits the European Union, leaving the Republic of Ireland in and the north out. (Charles McQuillan/Getty Images)

Today, after almost 20 years of stability and peace, Northern Ireland is open and without a physical border, thanks to a common travel area policy that existed before the EU and has continued as a component of the bloc's border-free treaty structure.

Young people from Northern Ireland like Edgar think nothing of the two-hour plus train journey to Dublin to party or to do business, something their parents wouldn't do. Back then, violence or long queues at the old militarized border made going to Dublin much harder for them.

However, with Wednesday's triggering of Article 50 of the Lisbon Treaty, this era of mobility and openness in Northern Ireland might be about to end. The U.K. and EU have exactly two years to agree on the precise terms and conditions of their rupture.

The spectre of this divorce has caused ructions throughout the United Kingdom.

There's probably more serious discourse about Irish reunification now than at any time since partition. - Kevin Meaghar, commentator

Scotland, which voted to stay in the EU, is adamant about holding another independence referendum rather than being dragged out of the EU against its will.

Northern Ireland, the other region of the U.K. that voted overwhelmingly against leaving, has a failed economy and is unable to survive on its own. It currently receives annual funding from London to the tune of $16.5 billion Cdn — so a Scottish-style bid for independence isn't viable. Yet there are mounting calls for Northern Ireland to leave the U.K. and reunite, after 96 years of partition, with the Republic of Ireland, an EU member.

"There's probably more serious discourse about Irish reunification now than at any time since partition," Kevin Meaghar, a commentator and former special adviser on Northern Ireland to the U.K. government, said in an interview.

Farmers from the border regions of south county Armagh and south county Down in Northern Ireland gather to bid on livestock at the Camlough cattle mart. Brexit 'would kill this area, business-wise, says Frank McPolin, the owner of Casey's Eurospar supermarket. (Don Duncan)

The Good Friday Agreement guarantees a path to reunification through a referendum whereby a majority of Northern Irish citizens must vote to leave the U.K. and join the Republic of Ireland.

Until now, that prospect has held no water economically or politically for most people in the province. A pre-Brexit poll, undertaken by the BBC in 2015, showed that only 30 per cent of people in Northern Ireland wanted to split from the U.K.

Then came Brexit. The entire political chessboard in Northern Ireland was shaken.

As the least developed and poorest region of the U.K., Northern Ireland, with a population of just 1.8 million, stands to suffer the most from a hard Brexit.

Crossmaglen, a village some three kilometres from the border with the Republic of Ireland, was a flashpoint of violence between pro-Irish paramilitary groups and the British Army during the "Troubles." Today, the peace dividend is everywhere to be seen.

A bus travelling from southern Ireland into Northern Ireland passes a Brexit protest sign along the stretch of road that seperates the two countries at Newry. A 'hard' Brexit will likely bring back a closed border with customs checks, wiping out Northern Ireland's significant cross-border retail sector. (Charles McQuillan/Getty Images)

Once signs reading "Sniper at Work" dotted the village's streets. Today, instead, a glitzy retail complex called Casey's Eurospar plies its morning trade. Customers fill their cars with gas, pick up groceries or grab coffee in the area's small café. Some 40 per cent of them come from the Republic of Ireland, south of the invisible border.

It would kill this area, business-wise. - Frank McPolin, supermarket owner

A "hard" Brexit will most likely bring back a closed border with customs checks, and this would wipe out much of Northern Ireland's significant cross-border retail sector.

"It would kill this area, business-wise," says Frank McPolin, the owner of Casey's Eurospar, as he dutifully sprays the plants in the window display of the supermarket. "We could handle fluctuations between euros and pounds, but we couldn't deal with a cut-off in the circulation of movement."

Outside, more people furrow their brows over Brexit, but for different reasons.

Disappearing subsidies

"We'd have to stop farming," says local farmer Patricia Bellow as she carries bags of groceries to her car. Bellow, like the majority of farmers in Northern Ireland, depends on EU farming subsidies that will disappear with Brexit. Subsidies and grants from the EU currently represent some 85 per cent of farm income here.

Hear more about a possible reunited Ireland on CBC Radio's The World This Weekend Saturday at 6 p.m. ET (7 p.m. AT, 7:30 p.m. NT).

All told, Brussels sends $630 million Cdn every year to Northern Ireland in the form of farming, infrastructure and peace-building grants. All this will vanish in 2019.

This spectre of hardship is beginning to cause creaking shifts in Northern Ireland's once dogged, pro-Union majority position.

Unionists — those in Northern Ireland who identify as British and who wish to remain part of the U.K. — have traditionally been the main obstacle to the reunification of Ireland. But Northern Irish Unionism is currently in deep crisis.

Catholic majority coming

Elections held earlier this month for the Northern Ireland regional Parliament saw Unionists lose their absolute majority for the first time ever.

The province's demographic profile is changing, too. Catholics, once a minority, are expected to tip into majority position soon, perhaps as early as the 2021 census.

And the rigid sectarian culture of Northern Ireland appears to be loosening.

"[Brexit] has changed all the dynamics of what we call 'soft' unionist or 'soft' nationalist," said Alex Kane, a unionist commentator and former consultant for the Ulster Unionist Party, in Belfast last week.

A view of the Parliament buildings at Stormont in Belfast, Northern Ireland. Soft unionists 'would not have been persuadable to a united Ireland two years ago but they will listen to that debate now,' says Alex Kane, a former consultant for the Ulster Unionist Party. (Clodagh Kilcoyne/Reuters)

"Those people would not have been persuadable to a united Ireland two years ago but they will listen to that debate now."

This core of "persuadables," made up of "soft" unionists, "soft" nationalists and non-sectarian voters like Peter Edgar, are thought to constitute between 20 and 25 per cent of the voting population. It is this group that could swing Northern Ireland out of the U.K.

"I don't know if a united Ireland is the best option. I don't know if remaining part of the U.K. is the best option," said Edgar. "All I can look at is what defines a happy life."

It's too early to say for certain if Brexit will bring "happy life" to Northern Ireland. If it doesn't, as is feared, it's the province's "persuadables" who may well speak up, with their votes.