While I believe a Pac12/Big12 merger is the best way for the schools in those two conferences to earn similiar money as the Big10 & SEC for TV rights. I find it tough to believe that Arizona, ASU and CU could think about defecting without there being more of a stir by the other nine members and insider articles by west coast media. Especially if their TV network is in dire shape.
AZ, ASU and CU all have greater value than any of the schools consistently mentioned as expansion candidates, including BYU. However, the prize schools in the Pac12 are USC, UCLA, Stanford and Oregon from a TV rights standpoint.
If there is any truth to the rumor, AZ, ASU and CU are the smoke and USC, UCLA, Stanford and Oregon are the fire and true targets of the Big12.
IMO if there is any chance of existing Pac12 schools joining the Big12, FOX is going to need to help facilitate such a move as they are the Pac12s network partner and own part of the Big12s TV rights til 2024.