I think if the Pac 12 expanded to 16 with four Big 12 teams, you HAVE to go to pods. All the non-California schools want access to California, so you couldn't go with a clean East/West split.
NW Pod
Washington, Washington State, Oregon, Oregon State
California Pod
Stanford, Cal, USC, UCLA
Mountain Pod
Utah, Colorado, Arizona, Arizona State
Midwest Pod
Whichever Big 12 teams
You play the three teams in your pod every year, preserving rivalries, and two against each other pod (one home, one away). This gets you to 9 conference games, and guarantees a road game and a home game against each region, rotated so that you can face every other team home and away within a span of four years. Also ensures each team plays a game within the state of California every year. It also ensures all California schools play each other every year, which was a sticking point when the league went to 12.
I like the general idea, but think it's preferable to play everyone in your pod every year, and two in each other pod (alternating years, so you play everyone at least once every two years).