The only way any Pac 12 school leaves is if the TV contract is problematic. If that happens, they will all want to leave.
Do you know how I know I am right about none of the remaining schools wanting to leave the Pac 12 unless the league is coming apart? Because none of the remaining Pac 12 schools have tried to leave the league. Do you think the Big 12 would have added UCF, Cincinnati or Houston if any of the Pac 12 schools had wanted in? Of course not. Unless you have "inside information", it is safe to assume that the Pac 12 schools think this is going to work out. If something happens to change that perception, they will all be running for the door.
See Old Big East (Syracuse, Rutgers, Cincinnati, West Virginia, Pitt, UConn, Louisville, USF) if you want to see what that looks like.