Why would you expect evil ESPN or FOX to bid on the next Big 12 media deal? The way you derail both entities, I would think you would be happy if ESPN/FOX have nothing to do with the Big 12 after 2031. Especially since they underpay for the media rights they have purchased. IMO the best hope for the Big 12 is someone like Skydance/Paramount+ or NBC/Universal.
You act like ESPN/FOX have a monopoly. They are the dominate players because they have been willing to pay the most. ESPN outbid CBS for SEC Saturday afternoon games. The Big 12 could have gone out to bid, but understood ESPN & FOX would pay the most. The Pac 12 could have given their media rights to Amazon, but university Presidents thought their visibility would tank on a subscription platform.
ESPN, FOX, NBC, CBS, TNT, etc. don't arbitrarily come up with an amount they are willing to pay for media rights. It's based on platform subscriptions they can sell and what advertisers will pay for commercial time. So if media companies think Big 12/ACC schools can attract comparable viewership to Big10/SEC then the Big 12/ACC will get paid comparable.
You can't have it both ways. ESPN/FOX evil monopoly, ESPN/FOX underpay, Pooling will bring 2-3x. The Big 10 (and NFL) got it right. Diversify distribution partners to strengthen negotiating position and maximize media rights fees.
Maybe you should add CBS to your monopoly diatribe. The NCAA hasn't taken March Madness out to bid in over 20 years. The NCAA most recently renewed a 10 year deal from 2023 to 2032.