Follow the money.
This whole thing is ESPN’s doing. To understand we have to go back to the previous realignment.
The catalyst for it was, likewise, Texas. Texas engineered this Longhorn Network deal with ESPN. To get content, the Big 12 adopted this “third tier” TV rights system. Each team would retain one football game, three basketball games, and buckets full of other sports. Texas’ went to the Longhorn Network; Oklahoma’s to the local RSN (most people believe that Texas pays Oklahoma some of its LN $$). After bouncing about for a bit, the other 8 (the Little 8) sold their rights to ESPN+ for a very small amount.
Every other conference shares TV revenue equally. Faced with this idea, the four teams in the Big 12 1.0 with the ability to get out, got out. TAMU, Mizzou, Nebraska, and Colorado. The remaining ones had no such options. So Texas found two mid-majors and got to 10. The idea was that Texas and Oklahoma would dominate the Little 8 and settle the matter between themselves, 9 years out of 10.
But it just has not worked.
On the field, Texas has made a series of bad coaching hires, but the main issue is that the five star athletes want to see if they can really make it at the top level. Beating West Virginia or Iowa State is not the top level. The SEC is. So Texas and Oklahoma have lost a lot of recruits to SEC teams, not the least of which is TAMU. Winning games over nobodies sounds fun, unless you are trying for the NFL.
Off the field, ESPN is losing $$ by the buckets full on the LN. One cupcake football game, a handful of early season basketball games, the other sports Texas plays, and endless reruns of Texas victories from decades ago is just not must-see-TV.
So Disney has a problem, and Texas has a problem. So, ESPN jiggers up Texas and Oklahoma to the Big 12, meaning it gets out of its LN deal, and the Big 2 get in the SEC. ESPN is happy, the Big 2 are happy, and the SEC is happy. And some sort of bone will be thrown TAMU’s way to make it happy too.
As to the Little 8? Do not believe a word about Kansas to the Big 10 or whatever. ESPN will point all 8 to an expanded AAC. The fix is already in.