Texas would have to get over itself before they would be allowed to join the conference. As it stands I doubt they are willing to do that. Perhaps they can make it as an independent; the problem is what do they do with the rest of their sports? Join CUSA? That would be a huge downgrade for all the other sports, especially bb, basebal, and their women's bb team.
If Texas were to join any of these three conferences it would be because of money and academics. Which of the three conferences has the highest academics--Big 10 and Pac 12. Which conferences command the most money and would command even more if Texas joined a conference? Which conference has its own very successful tv network? Which conference has the most popular teams in the country and an incredible fanbase? Which conference does ESPN fear the most?
I don't think any conference is going to allow Texas to join on its terms and keep its own network. The other conferences have seen what THAT does to a conference. So does Texas go independent and just disregard all other sports for the sake of their football team and precious tv network? There are only three conferences that are worth Texas' time--the Big 10, SEC, and Pac 12, but to belong they have to become another member.
Eventually, both Texas and Notre Dame are going to join a conference (unless of course the Big 12 stays together). The question is which conference will they join. Hell, Notre Dame is almost a Big 10 member NOW. Do they give up those rivalries to join the ACC? I think not. Unless Notre Dame really starts performing big time again, they are not going to be in a position to tell a tv network what to do; NBC or whoever, will tell Notre Dame what they will do. Right now, NW, Indiana, and Minnesota make more money a year than Notre Dame. Does Notre Dame continue to make less money each year as the lower Big 10 teams continue to make more JUST to stay independent? Or does the money and especially the academics of the Big 10 become too much. Join the Big 10 and their money and academic prestige immediately skyrockets. Join and the major tv networks REALLY want a piece of the Big 10. Negotiating is now controlled by the Big 10. Which tv networks want the Big 10 if Notre Dame and (or) Texas are now members? ALL of them. Iron out any differences and the Big 10, all of its members, Texas and Notre Dame make out like bandits--both schools and the conference know this. Especially the academics side and THAT is what will draw both schools eventually to the Big 10 as equal members. They might eat some pride but the results are much greater than any pride.
The Big 12 is the only conference willing to let Texas rule the conference and other conference teams are willing to be Texas' beetch and do their bidding. The rest of the Big 12 teams except Oklahoma are frightened to death that the conference might break apart so they are willing to give Texas whatever it wants to keep the conference together. Hell, they might even start giving Oklahoma whatever it wants to keep them, and take less money.
The problem is that Oklahoma now is as upset about Texas as Texas A&M was and it won't take much for Oklahoma to pursue other avenues. They are an attractive team for some conference--the SEC perhaps to go with Texas A&M? If Oklahoma leaves the conference, that leaves Texas as the only name team left in the conference. BYU is not going to join the conference if Ok leaves. Thus the Big 12 is unable to attract any decent teams to up its status as a conference. All the conference would be doing is filling holes.