My 2016 was a primary catcher sometimes pitcher as he entered HS. From his experience I would say it will be more and more difficult to do both. IMO one will step to the forefront and likely soon.
For my son it became clear this time last fall (so fall of his sophomore year) which way he needed to head. He lacks even average foot speed and while he doesn't light up the radar gun he can pitch and is unique enough to stand out. Once he became a primary pitcher things started happening for him with college coaches.
If your son's goal is to just play HS then let his HS coach guide this process and he will likely settle where the HS coach sees him helping the program the most or the soonest.
If his goal is to play in college and he plays on a good travel team get him on the field in both places and then listen to the signals that folks start giving you. I think it will be fairly obvious which way he should pursue if you really listen to what is said or what attention he does or does not receive. You might have to set aside how you see or have always seen your son. If that is the goal it is how college folks see him.
FWIW from what I have seen the path to playing college baseball is not easy for anyone but there are certainly a lot more pitchers than catchers on a college roster. My son's team has already had four 2016s commit. All are pitchers.