If that were to happen, the Big12 would be left with Baylor, Kansas State, Iowa State, Oklahoma State, TCU, Texas Tech, and West Virginia. All of a sudden, the other conferences will make their moves:

• The ACC would jump at one of the Big12 members, say West Virginia (as the rest are geographic outliers to the ACC) and tell ND to jump all in. Result, 16-team ACC.
• By adding TX/Kansas, the B1G, which has shown it doesn't care about adding quality football programs (here's looking at you Maryland), is at 16 teams.
• The SEC would also cherry-pick one of the remaining Big12 teams to get to 16 teams, say Oklahoma State because it keeps Oklahoma happy.

With that out of the way, the Big12 would be left with Baylor, Kansas State, Iowa State, TCU, and Texas Tech. So, to that pool of options, add Boise State, BYU, Houston, SDSU, UNLV. Does BYU get in? Who knows. But, the fact will be that whoever the PAC12 doesn't pick up will likely get picked up by the AAC/MWC and the Big12 will be dead.

The bottom line of expansion is this:
1) The B1G/SEC are the two top dogs
2) The ACC comes in next due to its geographic location and ability to add one more quality east-coast team.
3) The PAC is the weakest of the P5 conferences that will survive the next round of realignment because it is a geographic outlier and the teams that will want to join...that the PAC will be able to swallow...will likely be Big12 cast offs and G5 clubs.
4) Despite it's living in denial, the Big12 is on life support heading into the next round of realignment. If the Big12 is not VERY proactive, it will not survive.