Assuming OSU/MSU, Baylor/TCU, and Bama/LSU get in, how do both Clemson and ND get in? Even if the Pac-12 and Big 10 both self-destroy (which strikes me as unlikely), are they going to want to put in teams that have already played each other? As far as I am aware this only happened once in the BCS era (out of 16 games) and while I realize that was computer-driven, there is still probably a perception that we've already seen 'that game,' etc.
On the other hand, this leads to the bizarre situation that losing to another playoff contender hurts a team, which makes little sense. Also, the consensus view on ESPN yesterday, and that of Sir SEC on his radio show this week, was that an 11-1 ND would get in. Hopefully they are right.