I think there is a 0.00001% chance of him returning. Don't get me wrong, I would absolutely love for him to be back, we would be the biggest story in sports all of next season. Cooper will announce he is going pro well before the draft lottery, which is usually in mid May, so he won't know which team he is going to be stuck with, that doesn't matter.
The problem is that he needs to begin his rookie NBA contract in order to be closer to the 2nd contract which in 2030 could be something like 5 years for $500 million. So unless Duke can offer something like that, I just don't see it happening. I wish the NBA would change the rule on how quickly you can get to the 2nd contract, but this will be the way it is until that happens.