In short, given the current state of college baseball recruiting I think your son (with your help) needs to "get after it" right now. Let the college coaches decide what is his upside, and where he could potentially fit in a rotation. He has a recruiting advantage being a LHP...use it. It took my son 22 months to find the right fit based on what he wanted to get out of college. Lots of things happened in those 22 months. Some of it we controlled, and some of it was out of our control. Luck was part of it.
If you think he is JUCO or HA Ivy candidate then pursue it with everything you got to actually prove it out based on what your son wants to get out of his 4 or more years. I know from an Ivy recruiting perspective they have (already) identified some high school junior candidates and constantly sifting through others given the challenges of D1 athletics combined with stiff academic requirements. Lean on your high school, and travel coach to get you started....now. Of course there are many resources here to assist as well. Tick tock.
As always, JMO.