I don't really want to get into a contest with Idaho about which state is more progressive. Regardless, I don't think BYU or Boise St are on the Pac-12's radar at all.
I think Pac-12 expansion will probably be done in a different way. For instance, they might sell their TV deal jointly with the Big XII but otherwise remain an independent conference, content with 12 culturally-aligned schools. I also wouldn't be surprised if the Pac-12 again attempts some sort of scheduling alliance / loose merger with the B1G. They may also try to strengthen their deal with the Rose Bowl to ensure it's always a Pac-12 vs B1G champs matchup.
But ultimately, I think they're looking at things like selling direct to the consumer rather than thru cable and OTT providers. The Pac-12 has always been the most customer-centric league, and if they're building an even more forward-looking vision, then the type of sports they play, the rules that they play with, etc. would all be on the table to be more accessible to viewers.