Idea regarding NBA draft/age limit

Seeing the discussion about Silver's plans, I thought I would post an idea I've had for a while. I don't know if this has ever been brought up, but how about keep the current rule in place where players can leave after one year. What you change is compensation levels. Have slot values for each level of college completed. Of course you would still keep slot values for the portion of the draft the player is selected. You go to college for 1 year, you can get x amount, 2 xx amount and so on. The numbers would be the hard thing to figure out in terms of what would entice players to stay or go. This keeps with fair market principles, seeing as a more mature and developed (i.e. less "training costs") player can command a higher salary. Is this completely unrealistic and would the union accept this? Thoughts? Obviously we don't have a platform to purpose this, but it's fun to spit ball.