USC, Oregon. Those are absolutes.
The next two…. If they take two more would be UW and then probably Stanford. UCLA could be the 4th.
The Big 12 would come in and take best teams left based on national draw and geographical market share.
I would predict the team remaining of UCLA/Stanford and then ASU (Phoenix), Colorado (Denver), and Cal (lock in rest of Bay Area)
Utah is superfluous with BYU on board. WSU and OSU are the most endangered by far if USC leaves. Arizona is the least of the Arizona market and the CA schools are more valuable.