Why???? I don't see it that way. The players playing with their age group will start getting seen in summer one year earlier than the "on age" kids in their grade. They just cant get offered until that following year. There would still be an opportunity for college coaches to watch more games and see those kids again if they really want/need to but of course a bandwidth issue for them. Having an on age system below high school is the way to go and this perceived issue is not at all a good reason to keep the current system in youth. I think the rules can be different in HS, but I don't believe at all a kid has to move teams. great players get seen, great players get found regardless.
First off the minority of kids playing are getting recruited when you consider the total population of players | 
