On the surface it seems that the Pac-12 & Big Ten champs are locked into the Rose bowl, the Big XII & SEC champs are locked into the "Champions" bowl, and the ACC champ has no one to dance with... but is that really true? What about in years when either the Rose or "Champions" bowl hosts a semi-final playoff game? Here's one possible rotation scenario which is ideal for the Orange bowl:
Under this scenario, whenever the Big Ten champ is displaced from the Rose bowl, that team would find a soft landing spot in the Orange bowl. Likewise, the SEC champ would have a backup plan as well.
Why would the Big Ten and SEC agree to this? Because it would allow those 2 conferences to earn more than the Pac-12 and Big XII. Simple as that.
Of course, the Orange bowl has a backup plan also - Notre Dame. If the Irish are ranked higher than any available Big Ten or SEC team, the Orange bowl would select Notre Dame instead.