the problem is the NBA doesn't care about the NCAA and won't put the rules in place on their end to make the system work. They put the 1 years rule in to protect their teams from their own stupidity because they were missing on too many HS kids in the first round.
If the NBA won't set a get drafted and sign or go for at least 2 years rule in place along with the NCAA, the NCAA can't do it. So the NCAA needs to control what it can control which is the scholarships. If kids want to leave and the NBA wants them, let them go, but make it hurt the school if they do it a lot and the incentive to do it all the time like KY is removed. Rules and regulations will always be outsmarted, incentives will usually drive the behavior you want.