Thinking through this some more, IF the Big 12 is going to eventually implode, this is what I'd like to see:
The ACC brings Notre Dame football into the fold as a full member, along with UConn.
The Big Ten adds Texas and Kansas (not sure what Nebraska is going to think of this since they fled the Big 12 in large part because of Texas).
The SEC adds Oklahoma and West Virginia. I know what the demographics are and they don't matter. With the ACC solidifying itself there are no more large states to conquer, so we take the best football. Missouri moves to the West division, and Auburn moves to the East. I don't think the Iron Bowl dies, but the Tennessee series likely goes away. The Iron Bowl is probably moved to mid-October in order to avoid a rematch a week later in the SEC championship. Alabama and Oklahoma will play the weekend after Thanksgiving. Yes, the SEC West gets even more difficult despite losing Auburn and gaining Missouri.
Texas Tech, Oklahoma State, TCU, and Kansas State join the Pac 12. None of them are the Pac 12's first options, but if you are going to take on Utah, you'll take on these 4 as well in order to gain a foothold in Texas as well as the Central Time Zone.
The Big 12's leftovers are Baylor, Iowa State, and whatever AAC teams they add this year. And those AAC teams are going to feel pretty foolish at this time, but I suspect they will find a home somewhere. Perhaps back in the AAC, depending on how that conference responds to losing said teams this year. Maybe they don't add any C-USA teams, for example and have room to add back teams that leave.
Anyway, few care about Iowa State, and even less care about Baylor after all this scandal they are going through now so it's not that big of a deal.