If Stanford leaves the Pac 12, for the B10, that will kill the P12 as a conference. They simply cannot afford to lose any of Stanford, Oregon or Washington. If Arizona left for the B12, they could fill in with SDSU, but they could never replace one of the main three for the media side of it.
It's easy to draw a path for the B10 to take Stanford, putting more pressure on ND to join in the future, and the wait to see what happens to the ACC GOR agreement. I still think in their perfect scenario, they want ND, Stanford, UNC and UVA. That would give them the 3 best brands in California and strengthen their position on the East Coast.
When that happens, Oregon and Washington will then have to swallow hard, and join the B12 to stay relevant.