Byu views contracts differently than you. The Indy Bowl has already been out to three games and byu may feel differently than you. I’m not saying they won’t opt out but I wouldn’t be a confident as you. The agreement was multi year and byu may feel a sense of loyalty since this is only year they can play in the Indy Bowl due to them joining the Big12.
Go listen to Mitch Harper’s podcast from a few days ago. I’m guessing his sense of direction is better than some fan.