Well, his applications are all out, so waiting to see options is great. Once those decisions are in, he could call the coaches and pursue a potential walk-on route. Also, club baseball may be an alternative at some schools.
Most high academic D3s carry a pretty steep sticker price (don't know your financial ability) with no academic scholarships - but on the back end, lots of great employment opportunities.
I do know several seniors (including one who got an offer to Indiana during the summer post-graduation) who get offers all the way through the year.
on the JC front, would he live at home or go away to a JC? The few kids I know who went away to a JC had big problems balancing academics, serious dedicated baseball, social lives, haircuts, eating, paying rent on time, etc. Lots of additional (and unnecessary IMO) pressure for a kid just trying to find the student union to have to live on his own.
But, you're casting a wide net and keeping options open; all he can do now is play well and continue getting good grades and not succumb to senioritis.