Was thinking about this the other day.
Say they add SDSU and BSU
OR, WA, UU, Stan, BSU, ASU, WSU, OSU, Cal, SDSU >
OSU, Bay, TCU, KSU, BYU, TT, WVU, CIN, ISU, UH.
The difference in the football teams is minimal and you can argue the Pac 10 has bigger names at the top. The key then to ending the Pac 10 is taking out Oregon and Washington. That would clearly separate the big 12 on the playing field.
Now if they added four more G5 to match the 14 teams the Big 12 has then their bottom fourth would clearly be worse than the Big 12.(ie SMU, UNLV, FSU, SJSU) don't match up with CO, AZ, KU, CF.
So one way or the other need OR and Wash to move on.