daveccpa,
I am sorry to hear about what your son is going through! I hope that you will post and let us know how he is doing as he works his way through recovery.
daveccpa - Two of my boys have had the ulnar nerve surgery (while in high school) - one a complete transposition and the other "just" a decompression. Recovery from the complete took about 4-6 months and he was able to throw/pitch again with no pain. He also had some scar tissue and a bone spur scraped from his elbow during the surgery. Eventually though he did give up baseball in favor of football, but lifelong (and remember that's what matters most here) - he has had no issues with the elbow. Child #2 with just the decompression took 3-5 months to fully heal and is still pitching - freshman at D2 school. *Both* children had the some "comment" about not being able to play again from the doctor - I think that's in the manual somewhere.
As much as it's a bummer to be without baseball for now, one can come back from this. It will be hard work, follow what the therapists recommend. Whether he plays at college or not, there are always men's leagues somewhere looking for young players, so baseball isn't over if he wants to play. It would be more of a bummer for him to not be able to play catch with his son(s) - gotta think big picture and long term.
daveccpa - My son had ulnar nerve transposition surgery his sophomore year in college and ended up having a very successful 4 year college career. During his senior year he was a combination starting weekend P/DH/starting RF. Depending on the severity of the injury, full recovery can definitely occur.
Best of luck to your son. My prayers go out to him for a full recover and the hope that he will continue to play.