The Pac 12 has no use for a weak religious school.
The way things are going for the football program now, they eventually won't even be able to attract good opponents, let alone entice a Power 5 conference.
Their best bet is going to be to drop football down to FCS and join the Big Sky Conference so they can do battle with Weber State & Southern Utah University. Maybe Big Sky gives them full membership for the other athletic programs.
They left the Mountain West, and the Pac-10 (now Pac-12) passed them over. Last year the Big 12 passed them over. BYu is an independent in football, most of their other sports are in the West Coast Conference. Gymnastics is in something called the Mountain Rim conference since the WCC doesn't do gymnastics.
BYU left the Mountain West conference in the middle of the night. Did not give the other schools any notice. The other schools were left scrambling.
BYU thought they were to good for the other schools and thought they would become a mighty independent school with it's on TV contract and other schools would love to play BYU. Did not work out like they thought.
I have no sympathy for BYU because of the way acted. In other words, the Mormon way. Mormons think they are better than anyone else.