Wait and see where he gets in, and have him go to accepted student visits at his top 2 or 3 choices (sounds like he already has the U of C visit scheduled, so wait and see what his other options area). There is no rush to decide (don’t let housing pressure guide him, either). If Chicago is the right place, he will know for sure after visits to his top choices. I would tell him to keep an open mind until after acceptances are in and visiting a couple of schools. One of my kids changed her mind after accepted student visits a few years ago (which included a visit to Chicago). There is no good reason for him to rush his decision.