Practice will be what determines how he will be viewed by the coaching staff.
What you don't want to see happen is for him to burn a year by playing in one or two games and it happens very often at large programs.
If your son plays other positions it will be helpful, keep in mind that your bat keeps you in the lineup.
How ones does in the season determines where the coaching staff will place a player in summer and so does their prospect status. This should be a discussion with the coaching staff before a commitment, will he get an opportunity to play in summer somewhere.
Have a discussion in advance with him going to a D2 or 3 (in a year) if he feels he needs a change due to lack of playing time (in other words it doesn't work out). If this is what he wants then its his call.
Keep in mind that he will not sign an NLI so the possibility of another opportunity coming up still exists, I would keep the door slightly ajar, this would include JUCO.