PT and athletic training will definitely require graduate school. AT is changing so that the bachelors degree is not enough to be a trainer. I don't know OT, but that might too.
The transfer of credits issue is very real. My older guy just transferred from a high academic D1 to another four year school and not all of his courses would transfer. It was quite a shock to us.
Any path has its issues. Going the JC route will require beginning the college recruiting process immediately again to try to get to a four year school.
Regarding pitcher development, I don't know JuCo's specifically. IMHO I haven't seen or heard about tremendous development under the hood of most colleges. That doesn't mean there aren't good pitching coaches...there are and my oldest has one now. We've seen most development done by the pitcher on his time, e.g., winter and summer programs in particular at places like Driveline.