Why not allow these kids to enter the draft but return to school for as long as they want. That way they get the financial security (whenever they choose to enter the L) and they can stay to round out their games and/or obtain a degree.
Is there even a point? Is this even a problem in your opinion? I think the NBA can do as good a job as any college of developing players IMO, tho its prolly not best to have underage/immature kids going on a country trips with NBA vets.