2016: African kids start getting into basketball. The older generation tries to convince them that soccer is the greatest sport in the world, but alas the younger generation is more interested in basketball. At first, these kids are fucking awful. All they do is jack up insane 3s (trying to emulate Curry) and bully through people (LeBron). There are a few standouts, but overall these kids suck.
2020: With 4 years of playing under their belts, we start to see growing competence in players between the ages of 10-16. Emulating Curry no longer means jacking 3s, but instead completing difficult combination dribble moves. Instead of bullying through people, the stand out players start facilitating their teams' offenses by scoring at will and setting up teammates with easy shots. As interest grows throughout the continent, more kids get interested in the sport. Heck even local militias gain interest in the sport and start playing.
2025: It's official, basketball is now the next rising sport in Africa. Kids (and young adults) everywhere are setting up makeshift hoops, trying to get a taste of the future. Athletic freaks (who before this outbreak would never have heard of the sport) are watching clips of Giannis Antetokounmpo, Kawaii Leonard, Andrew Wiggins, and other NBA stars, and framing their games around them. Unfortunately, much of Africa remains hostile. Militias begin organizing 5v5 games where the losing team's players are killed. A video goes viral of Ugandan teenagers being executed after one of these games. In the video is a basketball and a wall with the words "ball is death" written on it. This video haunts NBA players, reminding a lot of them of their difficult childhoods and individual struggles of getting out of the hood. Collectively, NBA players and the Players' Association donate $20 million to the formation of youth leagues across Africa. Facilities are built, jerseys and basketballs are sent over, and referees are trained.
2035: Militia is still an issue, but young basketball players looking to pursue the sport do the best they can to stay away from trouble. A few 7 foot wings/forwards and 7'4 centers are making a name for themselves and getting recognized by NBA scouts. Three of them get drafted late in the 2nd round of the draft, but two stay home due to uncertainty that they will succeed in the world's toughest league. One player, Kelena Ogwu (the 7 foot wing), tests his skills at Summer League, but he is clearly not ready for the bright lights. Upon returning home, Ogwu gets the idea to start a basketball league in his native Nigeria. This is an instant hit with the locals who want to watch Africa's best stars on the court. FIBA also approves and they begin funding the ABL (African Basketball League). 8 teams are created, 3 of which owned by Joe Lacob, who is lightyears ahead, and the other 5 owned by other NBA owners. These teams play in Nigeria, Ivory Coast, Senegal, Kenya, South Africa, Zimbabwe, DR Congo, and Madagascar.
2040: The ABL is booming. Nigeria has won 4 out of the first 5 titles, but now their star player Ogwu, at the age of 26, is finally going to the NBA. There is parity now in the ABL; any team can win. More and more African teenagers are graduating from their youth basketball teams and going straight to the ABL. The pay isn't great, but it's better than nothing. African basketball is no where near the level of the NBA, but this is just the beginning.
2050: The ABL is now being broadcasted in the states by ESPN, with renowned African broadcasters Jeff Van Gbadamosi and Mark Jakande. Americans are amazed at how athletic some of these ABL players are. At this point, the ABL has now lost 15 players to the NBA since its creation. African superstars want to get paid more and test their skills in the NBA. Some are doing very well in the states. Kelena Ogwu is wrapping up a Hall of Fame career where he won 2 championships with the Suns. His impact is clearly more than just on the court, as it is very common to see his jersey being worn across the U.S. as well as Africa. The ABL continues developing young talent, while the NBA plucks it away right as these players reach their athletic primes. The ABL is the NBA's feeder league.
So to answer your question OP, there is no conceivable future where the NBA isn't the clear-cut dominant basketball league on Earth.