If the money remains competitive, I don't expect anyone to leave the Big 12. I haven't heard a compelling case yet about why the money won't be competitive.
OU is probably going through the best period of success in the history of its athletic department. OU is one of three schools in the country with a $1B+ football value. The Sooners have won 11 team national titles since 2013 in 4 different sports. That's not including the men's tennis program which played for a team title 3 different times in that span, a men's basketball program which made a Final Four and produced a Naismith winner, a football team with three straight Big 12 titles, a Heisman winner, two CFP playoff appearances, and two Sugar Bowl wins in the last five years.
So why all the bitching from OU fans? 1) there's probably a troll op fomenting some dissatisfaction from OU fans, 2) there's some residual fan embarrassment/resentment from the "wallflower" fiasco and fallout, and 3) there are still a couple legitimate problems with the Big 12 that nobody seems interested in addressing.
There isn't a helmet school within the conference to visit Norman (and moving the best CFB rivalry in the country from the State Fair to a home and home isn't an option.) That makes the home schedule look like trash every other year. And the academic standing of the conference took a major hit. Four AAU schools left and we replaced them with WVU (barely in the US News Top 200) and TCU (really good undergrad perception but a non-research university.) That academic hit probably means more to OU than Texas since the Longhorns' academic bona fides are established locally and nationally. OU is much improved academically in the last quarter century but is still nowhere close to where the big money wants it to be.
On the whole though, the Big 12 is fine. Olympic sports are great. Other than Texas sucking for a decade, Big 12 football has been good. OSU, TCU, Baylor, and K-State have Big 12 titles this decade. TCU is playing better football by far than anyone who left. When Herman starts winning 10 games a year, the Big 12 will move back into the "top SEC challenger" spot.