The Big12 should add the large universities from the MWC and WAC.
Nevada, (31,000)
San Diego State ( 34,500)
Colorado State (26,000)
BYU (34,000)
Boise State(19,00)
Fresno State (19,000)
UNLV (29,000)
TCU (9,000)
Might not be huge name programs, but they at least have the $ and enrollment numbers to support facilities, stadiums, etc.
That would add 3 solid football programs and a bunch of middle of the road programs, but more importantly, large and expansive regional coverage so the longwhorns can sell their TV package.