i have a somewhat different view on all this. the b10 is waiting for a new commissioner before moving forward. kevin warren took the bears job because he couldn't have his way with b10 presidents over expansion. the bears job is seen as a step down for him, not up, albeit it puts him in line for nfl commissioner someday.
so, when the new guy takes over the b10 this summer, the picture will clear up. the fundamentals for oregon and washington moving to the b10 are strong bringing some west coast partners for usc and ucla. i believe that will eventually happen. if not, it's only because notre dame goes to the b10 and brings along stanford. but i just can't see the irish doing that.
after the b10 moves, the p12 shatters. then and only then does the b12 scavenge taking for certain the two arizona schools and likely cu, plus maybe utah, although i don't like that school. yormark could also move on stanford and california for the bay area market and as with the b10 to bring some western balance.
overall, i sense the big 10 will have to make the first move before the p12 bursts. if it doesn't, it won't, so to speak. those western academics really don't want to separate particularly to join a bunch of land grant schools out there on the plains.
the exception to all that would be if the b12 offers a grant of rights "out" to oregon, uw, and others. as aggressive as yormark is, that would not surprise me if/when it happens.