Your idea of global NBA teams is not really valid. Unless the teams are in North America, it isn't a realistic possibility. To begin with, there are huge time and travel costs for playing teams in Europe or Asia on a regular basis. Second, there are some very powerful, well established teams in the top basketball countries in Europe. They will put up huge opposition against a new NBA team. On top of that, people aren't just going to change their loyalties to the new team after supporting a team that has been around for over 50+ years (though not necessarily as a basketball team). The Euroleauge champions CSKA Moscow were founded in 1924. The previous champions, Panathinaikos were founded in 1922.

Basketball is the American sport with the most global appeal, followed by Baseball/Hockey, and in a very very distant last place is Football. Basketball has the potential to be huge, but I doubt it will ever be bigger than soccer. Over 2/3rds of Earth's population watched or listened to the final game of the World Cup and over a billion people watch the Champions League final every year. Now that's something that will be extremely hard to replicate.