I don't really post much but I came across this thread and felt like I could give your son some advice. I played high school and select ball growing up and played 3 years in college, 1 at a Junior College and 2 years at the University of Arkansas. The first question I think your son should ask himself is does he want to play in college. If he doesn't, then select baseball would be a waste. If he does, then he should continue to play select baseball and travel to as many showcases as possible. Neither myself nor any of my friends that are still playing were recruited from their high school games, so high school baseball is not that important. To be honest, college coaches think high school baseball is a joke. Where I was recruited were the showcases that my select teams went to, as well as individual showcases put on by MLB and college teams, things like Area Code.
Also, I would definitely tell your son not to give up. I played with a lot of guys who were late bloomers. If he wants any kind of pointers on baseball or the recruiting process, I'm always willing to help.