Football is the sport that drives conference realignment because it is the sport that brings the most money to the universities and conferences. But what the Big Ten showed with the additions of Rutgers and Maryland is that academics and geographic footprint are the conference's main focus.
With the FBS playoff set to start in 2014 it looks as though the major conferences are trying to get to 16 teams. The Big Ten, along with the SEC and Pac 12, seem to be the most stable conferences because they are growing, not shrinking.
Those three plus one more conference will all likely grow to 16 teams each, 64 in all. With the Big East losing its BCS automatic bid and several members—Rutgers to the Big Ten, Pitt and Syracuse to the ACC—the automatic qualifying conferences will have 63 members by 2014. If those conferences can force Notre Dame to join, then they will have the 64 needed for four 16-team conferences.
This means the Big Ten is looking for two more teams. The criteria has been made pretty clear: Commissioner Jim Delany wants an AAU member—11 of the 12 Big Ten members are AAU members since Nebraska lost their membership right after joining the Big Ten—that increases the conference's footprint and brings big money.
However, I believe the Big Ten would make a few exceptions to those rules if the right school wanted to join. A right school like the first school on my list...