The Big 12's best chance is to act quickly on the instability and uncertainty to add some schools. This creates more instability and uncertainty.
However, if the Big 12 is unsuccessful and the PAC 10 does not lose anyone else, then the PAC 10 will have the perception of stability. They took the punch to the chin, but kept their bearing. In that more stable atmosphere, the PAC 10 will be in rebuild mode and I fear that they will be a legit option for Kansas and a few others.
I note that it was reported that the PAC 10's "merger" proposal excludes BYU and UCF.