ESPN will want some solid games for the first 2 or 3 weeks and could facilitate BYU v. AAC matchups, like UCF, SMU, or Temple.
And, even with a full P5 schedule, ESPN and ESPN2 broadcast G5 v. G5 games...especially AAC games.
FOX and CBS may also want better early-season content, but they don't hold both sides of the contract in a BYU v. MWC scenario. However, I think FOX has already scheduled MLB games in some of its normal college football timeslots.