2K Sports are expanding the MyGM and MyLEAGUE modes in NBA 2K17. This year, you will be able to add more than 30 teams.
2K Sports explained more about the new features over on the NBA 2K17 Facebook page. Details of how you can start the new league can be seen below. You can add teams outside of the NBA.
Start with the current 30-team NBA, as it is structured now. Start a league with Expansion where you can instantly expand the league from 30 up to 36 teams (all with designs of your choosing). Or, you can start with a completely customized league (that can still include up to 36 teams) that may include realigned divisions, Expansion Teams, Classic teams, Edited/Rebranded NBA teams, Euroleague teams, and more.
You can also make your league look unique as customization is better than ever before. You can even download team designs in NBA 2K17 created by the online community. This is a cool feature if you are too lazy creating anything flashy for yourself.
2K Sports is also allowing you to expand your league during the off-season. More details about both MyGM and MyLEAGUE modes will be shared at a later date.