If the new league has black players, it will have the same issue as the NFL. The real issue is the degree to which blacks have become alienated from American mainstream society. If these disaffected blacks aren't careful, mainstream society will become disaffected from THEM. They won't like it if that happens.
You are correct. A new league dominated by disaffected black players from the hood will quickly become what the NFL is now. I still watch MLB. It is not BLM dominated yet.