Stanford is to concede.
At best, Stanford will be a Big12 affiliate w a scheduling agreement. ND's about as likely to join the Big12 as Stanford, I think.
As for UW & UO — I just don't know. If they think a B1G invite is within the next 5 years, I could see them holding together with Stanford & the remnants. I don't think either wants the Big12 one iota. And neither feels near the urgency of securing their future as the other Pac schools.