The 2016 Rio Olympics taught us that even when USA Basketball sends its B-team, the rest of the world still isn't particularly close. Without LeBron James, Steph Curry, Russell Westbrook, Kawhi Leonard, Anthony Davis and many others, the U.S. still won the gold medal game by 30 points over Serbia. There were tight games and uninspiring stretches along the way, but the final result was never in real doubt because of Team USA's overwhelming talent advantage.

That could change by the time the U.S. is going for its fourth straight gold medal at the 2020 Tokyo Olympics. The United States will still have the greatest and deepest pool of players to choose from, but there is some serious young talent emerging around the world. The 2016 NBA Draft was the best example of this, as 10 of the first 16 players selected were born outside of the U.S.

There appear to be four countries in particular that could have some legit star power by the time the 2020 games arrive. With apologies to Spain, Serbia, Lithuania, Greece and Germany, here are the biggest threats to U.S. basketball supremacy.

4. France

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Who's probably back: Rudy Gobert, Nicolas Batum, Nando de Colo, Thomas Heurtel, Joffrey Lauvergne

Who's probably out: Tony Parker, Boris Diaw

The next French team will have a distinctly different feel after the departure of Tony Parker, who announced his retirement from international competition last week. Parker has been the face of French basketball for the last decade, but it's possible the next generation could have even more success.

France should bring back a strong veteran core, led by Gobert's towering defensive presence. Nando de Colo (who would be 33) and Thomas Heurtel (who would be 31) could still provide offensive firepower in the backcourt, while Nicolas Batum provides two-way stability on the wing should he return at age 31 in the 2020 games.

France also has some exciting young players. Five French players were selected in the 2016 draft covering all five positions. Another wave of French-born talent is coming in the 2017 NBA Draft, with point guard Frank Ntilikina gaining hype as a potential top-10 selection and 7'2 center Jonathan Jeanne also currently projected as a first rounder.

The biggest addition of all should be Evan Fournier, who was strangely left off France's 2016 team in Rio because he skipped a preliminary tournament.

3. Croatia

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Who's probably back: Bojan Bogdanović, Dario Saric, Mario Hezonja, Darko Planinić

Who's probably gone: Roko Ukić and/or Krunoslav Simon, who will each be 35 years old.

Let's recognize that Bojan Bogdanović is a star in international play. His 25.3 points per game were four more than any other player at the Rio Olympics. He'll be 31 in 2020 and should still have one more good run left in him. And by that time, Dario Saric and Mario Hezonja should be coming into their own in the NBA.

Saric and Hezonja might be the next great international duo. Saric played well as a 22-year-old in this tournament and has rare talents as a playmaking four. Hezonja has outstanding potential as a shooter and scorer and at 21 years old is only starting to scratch the surface. They will be ready to roll in Tokyo.

Dragan Bender is on his way, too. It's incredible to think Bender will still only be 22 years old for the 2020 games, but the fourth pick in the 2016 NBA Draft was outstanding for Croatia in junior competitions and should have already carved out an NBA role by then. Croatia also has Ivica Zubac and Ante Zizic, a pair of 19-year-old centers who were selected in the 2016 NBA Draft.

2. Australia

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Who's probably back: Patty Mills, Matthew Dellavedova, Aron Baynes, Joe Ingles

Who's probably gone: Andrew Bogut, David Andersen

The Aussies watched their first Olympic medal slip through their hands in heartbreaking fashion in Rio, but a bright future should help alleviate the sting of the final minute against Spain. The Australians already have a quality system put in place by a good coach in Andrej Lemanis. They should have Patty Mills (Rio's second-leading scorer) and Matthew Dellavedova entrenched in the backcourt. They have a veteran shooter on the wing in Joe Ingles and a steady defensive anchor in the front court in Aron Baynes. Even without Andrew Bogut, that's the solid base.

The reason Australia's basketball future is so exciting is because of who is joining them. It starts with Ben Simmons, the No. 1 pick in the 2016 NBA Draft and possibly Australia's first NBA superstar. Point guard Dante Exum, the fifth pick in 2014, could be a very good NBA player in his own right by then. There's also the great unknown that is Thon Maker.

There also seems to be quality Australian players entering the college ranks every year. Deng Adel is expected to be a breakout player for Louisville as a sophomore, while Isaac Humphries should crack Kentucky's loaded frontcourt rotation. Another name to remember is Harry Froling, a 6'9 stretch forward set to debut for SMU this season.

1. Canada

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Canada hasn't qualified for the Olympics since 2000, but it's impossible to ignore the young talent base that's been accumulating for our neighbor to the north. Since 2011, there have been 10 first-round draft picks from Canada, with seven selected in the lottery. That includes two No. 1 overall picks on distinctly different career paths at the moment.

While time is running out for Anthony Bennett, Andrew Wiggins looks like a future All-Star as he enters his third NBA season. With Wiggins holding down the wing, Canada should also have go-to offensive options in the backcourt and front court. Trey Lyles is a 6'10 forward coming off a promising rookie year for the Jazz, while Jamal Murray comes to the Nuggets as the No. 7 pick in the draft after a great offensive season at Kentucky.

Canada also has a group of solid young veterans who have already realized their potential in the NBA. Point guard Cory Joseph has turned into a great defender for the Raptors, the Celtics' Kelly Olynyk has proven to be a capable shooter in the front court and Tristan Thompson is already one of the NBA's best rebounders. Each will only be 29 years old in 2020.

The wildcard here could be R.J. Barrett, currently the top-ranked high school sophomore in the world. He was born in 2000 and would be 20 years old in Tokyo. We're all so old.

It would require a massive jump for Canada to go from a non-qualifier to an Olympic contender in just four years, but the talent is there. Team USA remains on top of the world, but they can't get too comfortable.