I know there are a few possible gambles that could work when it comes to Big 12 expansion, but it seems pretty clear to me that, if you're a "Big 12" fan, and not just a Texas fan, you should be pissed that the conference didn't go hard after ACC schools back before Notre Dame became a partial member and their new TV deals were signed. THAT was how to save the Big 12.
There were two pretty obvious ways things could have been handled: The Big 12 could have gone it alone and started chatting with the southern 4 ACC teams (and actually, Miami, despite its issues, would have been a good place to start given their market, the sense of uncertainty they had if the ACC had split, and their connection to Florida State that, given the current scheduling climate, would have been difficult to maintain had the two schools gone to different conferences). Or the Big 12 could have gone to the SEC and Big 10 and said, look guys, we ALL would love to add some of the ACC markets to our conferences. If we work together, there won't be much of an ACC left to prevent it from happening. Let's agree to going to 16 teams at most in the first round and there should be plenty of schools to go around for everyone, even if someone didn't get their first choices. If anyone really wanted to go beyond 16, there'd be plenty of opportunity after the fact.
The ultimate goal would have been to snag all 4 southern ACC teams to begin(Miami, FSU, Clemson, and Georgia Tech) but even 2 or 3 would have been a great start. Ideally, that would take the Big 12 to 14 teams, and give them the start of an Eastern division (with West Virginia... and, ultimately probably either TCU or Iowa State having to "take one for the team" and travel a bit further). Then you make the big gamble. With a less legitimate ACC (or no ACC at all, if the SEC did the smart thing and snagged Duke and UNC to add a state and bolster their Basketball product with the sport's biggest rivalry... and the Big 10 grabbed Virginia and... someone. Lots of great options...), Notre Dame would need a home. And since the ACC wouldn't be around to offer partial membership, they'd be looking at either the Pac 12 (which seems like the distance would bother even Notre Dame), the Big 10, or the Big 12. In many cases the Big 10 might win out, but given Notre Dame's desire to be a national team, not a regional one, the Big 12 (now in Texas, the midwest, the southeast, plus a couple of closer schools in ISU and WVU), plus not having a formalized plan for 3rd tier media rights yet (which means they could help shape the media deal more than they would in the Big 10) might be the more appealing option. Especially if the Big 12 opened up the 16th slot to let Notre Dame choose (within reason) who they'd want to add last... whether it be a traditional power like Virginia Tech, a nearby school like Louisville, a traditional rival like Pitt or Navy, or another big state like NC State.
Honestly, if the deal included adding FSU, Clemson, the Atlanta market, and Notre Dame, the last school could be almost anyone, and each of the options I listed above would come with some sort of benefit.
That's what should have happened. Or something similar.
As it is? I don't see the Big 12 prying anyone away from the SEC, Pac 12, Big 10, or ACC. At least not without help. But it would be up to one of the other conferences to rock the boat first, and I'm not sure that's happening in the immediate future. So, while the thoughts of getting Georgia Tech or Florida State or Arkansas or whoever are clearly appealing, I'm just not sure I see why it would happen unless something happened to destabilize the conference they'd be leaving.
Plenty of "fun" ideas out there as far as UConn or Houston or UCF or USF or Memphis or Tulane or Cincy or what have you, but they're all gambles at best and some, including Houston (who is probably one of the best group-of-5 expansion options for SOMEONE out there... the Pac 12 perhaps...) would be waving a white flag and saying that the Big 12, as a conference, just isn't going to compete financially with the rest and it will be up to Texas and other schools who can to keep themselves at a competitive level money-wise. As a Big 12 fan, you may want to take one of the gambles. As a Texas fan I don't know that I see a reason to stop the 10-team experiment yet, but when I do I think the answer will be leaving the Big 12 (and probably taking a few of the schools with us).