Just for completeness less than 5% of all BB players would be able to get into their P5 school on their own. It isn't just one and done guys.
I have become a fan of just getting the O&D guys out of college BB as well. Will cost the college game a lot of high end talent but the PR/perception issues that come along with them isn't worth it and the NCAA has shown no ability to play the PR game worth a damn. But also recognize the NBA isn't really looking forward to eliminating O&D. It means they have to scout HS players a lot more intensely and they will lose the ability to see them play against college level players (big step up even from HS AAU tournaments). And they lose the one year maturation process and maturation validation that happens in college. They will now make more mistakes than they already do.
In part because the NCAA has lost the PR discussion regarding athletes, transferring is about to get a whole lot more problematic. There is an active effort that most/many think will be successful to allow transfers in FB and BB without having to sit a year. That is going to be a real wacky process which will drive coaches at all levels nuts.