Affordability is a HUGE factor in where most attend college. He may need to wait until after college to go southwards. With grades/gpa in the neighborhood of a 3.0 I would not count on any merit aid and would be careful about the price paid/value received for OOS options he would be accepted at. Definitely look at the instate publics- you are Mass residents now and that’s most likely your best bet for a B student.
btw- having a job, especially one in one’s field is a major reason people live where they do. Hopefully your son understands that life with an income is much better than downgrading the family lifestyle significantly just to stay in an area. Kudos to you for being willing to move. A history lesson in there for your son- how economic forces influenced populations.