The leadership of the University of Texas is torn four ways when it somes to conference affiliation.
On Academic Lines
On one hand their academics would love to be in the best conference currently available to UT for academics --- The Big 10. With it's academic and research consortium, the Committee on Institutional Cooperation, the Big Ten represents the kind of conference UT academics would love to call home.
Luckily the athletic department swings a big stick. The Big 10 firmly favors schools that are members of the 62 member Association of American Universities (AAU) - an exclusive fraternity of elite "National" (ie. doctorate granting) Universities. UT's strongest allies, the University of Oklahoma, Texas Tech, and Oklahoma State are nowhere near that. For UT to join the Big 10, they would likely have to leave most and possibly all of those allies behind, becoming regionally isolated.
UT pulls a large amount of their ability to market themselves from playing regional rivals. A schedule filled with Midwestern teams would be soul deadening for UT's often fair weathered fan base.
Additionally UT would lose all influence over the direction of the conference --- something that the leadership in the athletic department and at the university appear to rightfully consider an unnecessary poison pill.
On Academic and Athletic Lines
The more tolerable academic move concept is to build a UT ark and carry UT's allies (Texas Tech, Oklahoma, Oklahoma State, and maybe Kansas) into the Pac-12. The Pac-12's conference admission standards are frankly, a notch lower.
Academic knuckle draggers Tech and OSU are on a similar tier to Arizona State and Washington State. The PAC may not love the idea of admitting those two, but to land UT (for the Texas Media Markets, political clout, and UT's research dollars) the PAC-12 would make the deal happen.
UT would go from being the undisputed ruler of the Big 12 conference to being a somewhat influential minority party member of a PAC-16 or Pac-18 ruling senate, capable of rallying votes on some issues.
Athletically, UT and their ark members should be able to maintain their success in an enlarged PAC-12.
UT fans and donors look on this move somewhat unfavorably as they balk at the loss of influence and feel that they would be propping up "someone else's conference".
Financially this is one of the better moves from the perspective of the State of Texas. This would do much to ally the states of Texas and California. California has a lot of angel investors. This kind of expansion of their academic circles could easily lead to new emerging industries and the high paying jobs that come with that coming to Texas.
Additionally, the Pac-12 is a heavy research conference. Such a move would likely ramp up research at Texas Tech and Oklahoma, yielding an improved national view on those universities and the degrees they grant.
On Athletic and Jingoistic Lines
Texas is a conservative state. Conservatives fear change and will fearfully cling to the old ways, even if they aren't the most lucrative or optimal options.
There are plenty of people in Texas who do not want anything to do with a "foreign" conference. They proudly beat the drum about how good it is to get "unloyal programs" like Nebraska out.
That inbred mindset combined with the ability to actively steer the direction of the Big 12 has kept UT in a conference that is a combination of the least impressive academically, the least attractive to new members, and the most limited market-wise of the 5 power conferences.
UT can tread water here, but that would amount not leveraging UT into a lot more money for the state and it's residents and ignoring a dramatic improvement on the hiring power of a UT degree in other states.
It is short sighted, but that is the nature of conservative policy ("trust what you know").
On Fantasy Lines
Then there are those who think UT should just take the Notre Dame route and become an independent. I think their strategy recklessly ignores the needs of UT athletically and academically and would not yield any positive results.
The Longhorn Network was an effort to test those waters of independence. It drove a huge wedge between UT and Texas A&M and almost drove off all of the members UT's fans like to see UT playing.
It was in no way worth a couple million dollars a year to lose having Texas A&M tied at the hip with UT long term.
UT independence would piss off OU. OU has proven they can replace the UT game with another random power (BYU) and still do quite well financially in Dallas/Fort Worth.
For UT, the OU game is the key piece in their annual fund raising effort. The loss of that game would hobble UT athletics financially.
UT is reliant on appealing matchups to keep their fans engaged. There is just too much to lose there for UT.
UT has tangoed with the ACC. I would classify that as a lesser version of the Big 10 option above. The ACC is quite a strong conference academically and is in a lot of nice markets, but it has many of the same issues as a move to the Big 10.
UT's leadership concluded long ago that the SEC was not up to the academic standards of Longhorn scholars. Having to follow Texas A&M there makes it a poison pill for UT's powerful athletic boosters. Much like Notre Dame to the Big 10, UT won't be broken. It won't happen.
Realignment of the Big 12 could potentially ramp up the perception of that conference, but most Big 12 scenarios have an easily viewable ceiling.
The obvious conclusions
There are two (and a half) workable scenarios for UT. Take a UT ark to the PAC-12 or expand and enhance the Big 12 (...or build a new conference off the bones of the Big 12).
What do those scenarios have in common? These scenarios would appear to require Texas Tech and Oklahoma to come along. Oklahoma appears tied at the hip to Oklahoma State by Oklahoma politics.