Does your son have a good ear? If he does I think it is possible but he will have to practice 2-3 hours every day for the next 16 months.
But he will never know if he doesn't give it try. If he doesn't make it he will be very close I bet and could enter undeclared if a university and try the next year or attend community college and keep working on the list and reapply after 2 years. The church music director at my old church did that. Not that he wasn't good but money was really tight so he went to community college first and transfer over to 4 year college with a scholarship he earned.