The PAC-12 losing USC and UCLA has already created the “worst case” scenario. The PAC-12 is toast.
The PAC-12, has and will ultimately be unable to acquire a lucrative TV/Cable rights contract – that is with competitive income streams and brand exposure.
Oregon and Washington will lose patience. I expect the Utah AD and Coach knows it, and is working on a plan outside of the PAC-12.
Next year (or sooner) BIG-10 will accept, or otherwise offer, Oregon and Washington, and probably Stanford and California membership. The BIG-12 will go after Utah, Colorado and the two Arizona teams. Oregon State and Washington State will go independent, or go to the MWC.
Therefore, at some point this decade, Utah and BYU will have their (despised) storied “Holy War” game at the end of the year, albeit as part of the BIG 12.