My son is a 2021 also, but doesn't pitch (he's a 3B/1B), and plays for one of the best travel programs in our state.... So I'm familiar with that age group & the way things are working w/ recruiting etc
your kid has the "golden ticket" (lefty pitcher) & I applaud you for shutting him down when the shoulder issue came up.
There are a lot of 2021's out there throwing mid 80's these days. Every top travel team has several of them, and there are many throwing upper 80's/low 90's (i.e. Cruising at those velocities). That takes nothing away from your son. It is an achievment to be where he's at, for sure.... However D1's aren't recruiting the mid 80's guys right now. Your son is on their radar though, that's a great thing. They are waiting to see if his velocity increases while meanwhile keeping tabs on a few hundred other similar pitchers.
For now I would emphasize arm care, make sure his mechanics are strong, and get him with a high quality pitching instructor... Your kid is pretty close to D1 material. If he can be cruising at 88-90, somebody will want him for sure. It is way too early in his academic or athletic career to resign yourself to attending a Junior College.
Do what you can to protect his arm health while working on getting stronger & increasing the velocity, and if he can improve his grades & test scores that will certainly help...