1) The little schools in the Big XII don't want the conference blown up. If it goes, so does their P5 status. They're motivated, and will find a way to keep Texas in the conference, even if it means making concessions.

2) Lets assume that Texas feels like forcing the issue, and negotiates tough. Why would anyone assume that PAC12 schools and would be down for a deal that the Big XII schools reject? Texas won't get a better deal in the PAC12 - in fact, they'd probably get a worse one (and they'd be playing tougher schools, too).

There is no incentive to leave, especially considering the insane amount of leverage Texas has with the other Big XII teams. Their current deal is awesome - and they probably will never get another like it - but their best chance for a deal that favors them is to stick with the Big XII.