An interesting post where Silver tries to estimate the popularity of each school in each division to figure out how and if realignment of the major conferences make sense. +Sports)&seid=auto&smid=tw-nytimessports”>His conclusion:

Of course, the question that an analysis cannot address is whether through expansion a conference can become more than the sum of its parts — or if it instead risks becoming less.
The only two conferences that can feel completely secure right now are the Big Ten and the S.E.C..
They’re the two that have taken the most conservative attitude toward expansion over the past decade or two, waiting for programs of the caliber of Penn State, Nebraska and Texas A&M to become interested before increasing their ranks. They’ve been rewarded with extreme loyalty among their fan bases. In a sport where rooting interests are so highly localized, that goes a long way toward explaining their success.