They'll be using the school's facilities, after all, and you are right that without that affiliation, they'd lose a significant number of fans. A lot of people (myself included) are only fans because they or their parents are alumni. If I moved to Ohio or something and lived in Buckeye country, I'd probably follow Ohio State, but I think chances are slim I'd ever really buy in and become a fan (Though I imagine my kids would be). I just don't have a meaningful connection there.