I feel like you're thinking a little too small-bore.
...Not at all, it will be about Texas maximizing money, influence, opportunities to stay the big fish, politics...it will be complicated
The Pac 16 wasn't about choosing a current TV package to glom onto, it was proposed as a paradigm shift for the sport.
No, it was Texas bringing along there posse, going California, & University prestige
And SEC with Texas and Oklahoma would be that to a factor of ten. All discussions of conference strength are over, forever, at least for the number one spot. One conference permanently leaving the rest behind in terms of on-field quality. And with the nationalization of college football interest, plus the depth of cultural penetration those programs have in growing areas of the country, you at least create the possibility of leaving everyone else behind revenue-wise as well. And in a way which is not reliant on running two-bit cable bill hustles on local grandmas, that's a juggernaut to be reckoned with in any media environment, because it's such an arsenal of must-see programming.
Quite frankly, SEC has already left the B1G behind in Football, but it isn't about conference football superiority, for Texas it will be about Texas Football opportunity, they can make more money & have a perfect setup in B1G West, there will be way more in play than Texas wanting to make the SEC the #1 Football conference.
The Big Ten can't offer Texas that. The Big Ten's offer is a handful of upfront cash and a fake sheen of prestige for the University. Which is good, but it's not THAT.
It's always going to be tough for Texas to make that leap if they can keep a pile of money all to themselves and beggar their neighbors. Exceptionalism seems to trump genuine ambition among that fanbase. And OU is key to the plan and whether they can break free of OSU is an open question.
This isn't about the fanbase at all. Texas president/board will make the call and it will be way more complicated than creating the best conference, no doubt Texas will be negotiating for prestige, power, money & there political circle in general. IMO, OK depends on the situation, I think they are probably hard pressed to leave OSU for dead if the B1G 12 is kicking, but Texas leaves & I think OU will be able to save themselves in a crumbling Big 12. Not sure anyone knows the full story from the last round, but there were plenty of rumors that the last time the B1G was OK's first choice, I'd be very surprised if they followed Texas to ACC in a deal where Texas has negotiated a special deal with the conference.
But if the logistics can be ironed out, the only parties I can envision saying no are the Vandy's and Kentucky's who would just never be able to compete. But all that money is tough to turn down.
Absolutely no one in SEC would turn down Texas and/or Oklahoma, except probably Texas A&M on Texas if politics will let them. so that isn't the question, it is where does Texas want to land and who wants them bad enough to start handing out extras, which is why I think ACC is the favorite, then B1G for the best combination of money/academics, or maybe PAC for combination of Academics & flexibility to bring friends