☝I hated the NBA taking High School players, but now I hate the one or two years and done. I think that move has hurt College basketball the most.
Just go back to taking the best right out of high school and make a scholarship in all college sports a contract for 4 years. Give them a reasonable stipend along with the full ride, and if they leave before the 4 years then they have to pay only the Stipend back. Make sure the lawyers on both sides check the legality of the contract like any other contract, crossing all the I’s and dotting all the T’s.
The one and done thing was a terrible deal for college basketball. That said, it won't be much better as long as players leave the first time they show NBA promise. The NBA picking up the MBL rule would be great for college basketball and the NBA. Let players that just want to be pro go the D-league route (or straight to the pros if they're good enough). Make players that enroll ineligible for the NBA or D-Leage for three years (or until whatever birthday; whichever comes first). This would be good for the NBA because they'd get to offload some development to the NCAA, and also they'd pick up some more affluent fans as college basketball fans followed former players to the NBA. It'd be good for the NCAA because it'd let them actually develop some teams while also not wasting time with players that have zero interest in college. It'd be good for the NBA players union because it would cut down on the competition coming down the pipe for a little while.
Amazingly, the NBA players union fights against age limits. Possibly the only union in the US that will not do what's in their personal interest just because they want to do the right thing.