Teams do that now. Penn St. dropped Pitt from their regular rotation as did Florida with Miami and in turn cycle cream puffs through their schedules. If the Florida legislature would let them drop FSU, they probably would.Plus, as has been said, if they do that, you will see true gimme games scheduled vs the occasional OOC matchups that we see now. Say goodbye to Bama/Penn State, Florida/Florida State, ect. No need to risk those potential losses.
In actuality, a playoff would result in teams scheduling bigger OOC games to increase exposure, as those games would have no bearing on the playoffs, since conference champs would get automatic bids (same as happens in B-Ball).