I don't think it changes a lot. The top guys already had the chance to go to the G League, get paid well, and not go to college. Only a few people took advantage of that per year. NBA teams are still largely not going to want to take a risk on someone they haven't seen play any real competition. There are clearly going to be exceptions to that, like Zion could've gone straight to the pros, maybe a guy like Banchero. It will certainly change it a little bit, but not too much.
I think I'd like to see the ability to be draft eligible going into college, and if you don't get drafted you just go to the school you were committed to. That certainly would complicate some things, but it could lead to better players staying in college longer as well.