Collins thinks a lot of himself and I doubt NW has the cash to pay him or build the type of facilities he will want. With that being said, Butler and Gonzaga consistently compete with the big boys. Duke seems to be the obvious fit, but he could be out after this season if the right Big East / ACC team calls.
Northwestern has the cash and is starting a $110 million renovation of Welsh-Ryan Arena after the season is over. I think Collins wants to stay in Chicago, raise his kids there, and build his own successful program.