It depends on how things shake out. If Stanford leaves to go to the Big Ten with Notre Dame, Oregon and Washington's interest in the Big 12 probably increases. Adding UO, UW, ASU and Utah is a far more valuable move than adding CU and Zona and hoping for the best. If the Big 12 wanted to speed up that process they could try to offer Oregon and UW something they want right now, flexibility when it comes to GOR. It's a gamble but if the Big Ten doesn't come calling, it could work out for the Big 12.
As for the ACC, I think there's a chance there are some more valuable brands then you think. These big contracts make expansion harder and harder. It's likely IMO that at least a couple of Miami, FSU, Clemson, Louisville are available.
Remember, Arizona and CU are pushing for this the hardest because they understand they're the least valuable pieces that are being talked about. They're concerned about being locked out if the PAC falls apart. It's notable that ASU and Utah do not seem as ready to make a move.