Great topic. These numbers on par with what I've learned and heard. Roughly 70% give or take.
A buddy and I very much disagreed on how many would return, but I "won" by surmising the majority would. He is logical and looked at it with reason and thought a 20% return rate would be on the high end of things. The logical move is to get on with your actual career and life. Me, the cynic, thinks that an alarmingly high percentage of players and parents have delusions of playing pro ball despite the numbers/math. This generation has been playing travel ball since age 8 and swinging $300+ bats since the same age. They've had high dollar private lessons and many have gotten on airplanes to play little league baseball. Many were given more of everything before they reached puberty than former pros did their whole lives. In my mind, this generation of players and parents will release their grip from the pro ball dream only when it's pried from their cold, dead fingers. Incredibly hard to stop a train that is carrying that much time and money investment. The optimist in me wants to believe that kids are coming back because they love the game and want just one more year to play it.