If the PAC 12 becomes the PAC 16 with Oklahoma, OK ST, Texas and some other Texas school (TCU or Houston are more likely than Tech, IMO), I think the AZ and MTN schools will balk at a division that cuts them out of CA permanently. Right now the CA schools get a scheduling concession so they play each other every year (so the rest of the south play Cal and Stanford less than we play the OR and WA schools). I think that disappears and either all 8 schools in the East get a concession that they play IN CA every year (a very difficult thing to do, even with a 9-game schedule) or, more likely, they move to a zipper format (or a CA-only zipper) as follows:

Zipper:
Each division includes 1 OR school, 1 WA school, 1 NOCAL school, 1 SOCAL school, 1 AZ school, 1 MTN school, 1 TX school, 1 OK school. Then you get a cross-division game against your rival, and your other one rotates every year (not home and away, you get a new school every single year). Put Texas and Oklahoma in the same division so they also get to play every year (rather than forcing Texas to pretend their rival is Houston or TCU, like the fake forced rivalry between Utah and Colorado). Everyone gets to play 1 game in Texas/Oklahoma and 1 game in CA (the two big recruiting areas). Oklahoma, OK St, and TCU/Houston probably hate it because it means more competition in Texas, but Texas probably doesn't care because they're still Texas.

CA Only Zipper:
Divisions remain as they are now but Utah/Colorado get put in the North and Stanford/Cal and USC/UCLA trade places with someone from the other division, so there's one SOCAL and one NOCAL school in each division.