951dad, I'm so sorry to hear about your son's troubles. It's hard to know what caused them, but as you say, what's done is done and your family needs to move forward.
You would be wise to not run the scenario through your head multiple times, as I'm sure you'll be tempted. Most likely, any second-guessing you do will only add to the hurt and frustration and possibly bring on bitterness.
It sounds as if your son is working hard to maintain his skills and if he is as talented as you allude to, he most likely will be able to play college ball. I would encourage you to find a high-level summer team for him and let every college know about his schedule. My son had 2 or 3 summer teammates commit after graduation, so there are definitely coaches still looking to fill gaps at that time.
If you are unaware of teams in your area that can provide the needed exposure this coming summer, please send me a PM and I'll be more than happy to confidentially help you locate one.
Best wishes to you and your son. Please keep us updated on how his spring and summer go!