They used to have Euroleague Teams, they already have WNBA in the game.
I'd go for International teams and a number of leagues from around the World.
Get the FIBA licence and have all International teams, for both men & women. Work it in MyGM where you can control a national team and have World Rankings that change as you play.
On the club side it'd be good for MyCareer, perhaps they should give you the choice of where you want to start your Career. Like maybe NCAA, or Europe, how about China or Australia?
2K should ditch the NBA name and go with FIBA, try and grow the game Worldwide like EA does with FIFA. There are top quality sides in Europe and I don't really know too much about the Rest of the World, all I really know is the New Zealand Breakers who play in Australia's NBL.
I know the British Basketball League would never be in but would be nice to have some representation.