If this were to happen, do you think the BCS tries to take the easy way out with another TCU-Boise matchup?
No doubt. There is no way the Rose Bowl lets Boise or TCU play IMO.
Because of fan appeal and Revenue they get pushed down to the level where they compete fan wise with the other schools in the pool (ACC and Big East). At this point they get paired together.
If I were in charge of making money on a bowl game, I would rather have runner-ups from the SEC, Big 12 and the Big Ten. I don't think this will happen because it would cause a uproar, but as far as money goes its the best bet, so we will see...