My son knows he always has a roof over his head if needs one.
He also knows moving back in with either his dad or me should never be his Plan, it should be what happens if his Plan doesn't work out.
Given the fact that he won't be saddled with a lot of student-loan debt when he graduates, and that he has ample opportunity to save $$ now while he's in school, and that he's going into a field with decent starting salaries, and that his dad has lots of connections in said field, I'd be really surprised if it ever happens.
I'm laughing thinking about how much he would hate it. LOLOL