for me:

1) Big-12 goes back to 12 and BYU is NOT one of the two schools. BYU would be out for a veeeery long time and probably permanently.

2) The P-5 conferences all go to a 9-game in-conference schedule, making scheduling even more difficult

Those two things happen on top of a G-5 guaranteed spot and BYU will have to find a G-5 home IMHO.