The ACC footprint is at least twice as big as the Big 12's. Notre Dame now enjoys an affiliation with quality schools in Boston, New York, Virginia, North Carolina, Georgia, Florida, etc. There are WAY more ND alumni and fans in those markets and surrounding areas than in Texas, Oklahoma, and Kansas.

IMO, Notre Dame would consider full membership in the ACC x100 before the Big 12. And, if ND wanted a Texas presence in conference, they would help the ACC to add a Texas school or two.

In reality, the Big 12 has absolutely no incentive to expand. None. Their current 10+-year TV deal is paying the 10-members as if there were 12 teams. In other words, they are making MORE than the market rate. There is no full expansion unless they can land a Notre Dame or Florida St (or an SEC, Big Ten, or PAC 12 power). No other teams can deliver enough for the Big 12 not to lose money on the per team payouts, let alone increase those payouts.

So, the football only track is an option if expansion is desired - ie, in the scenario where Big 12 can't get CCG deregulation that allows for the Big 12 championship game with 10 teams. And BYU and SDSU could be excellent options and the lowest hanging fruit.