I agree with this post. No way BYU and Utah and Colorado are going to effectively take the place of UA and ASU in the Pac (west division/conference).
If this kind of massive realignment were to happen and it very well may, I think logic dictates that they at least try to combine geography along with tradition.
Meaning traditional conference teams and rivals will stay together as much as possible. To me this would mean that it is easier to have ASU and UA in the west with the traditional PAC teams (after all they have been together for over 40 years AND Arizona as a state is closer to Calif (the "west" coast) that the state of Utah (yes, there is a state named "Nevada" that is between Utah and Calif, while Az already sits right next to Calif. I would also argue that the demographics of Az and Calif go better together (i live and grew up in Calif, served my mission in Az and went to BYU, so I am pretty familiar with all 3 states).