You are so tunnel visioned on ESPN & FOX. They are just two players that have been willing to pay the most over the last 20 years for live sports. ESPN for the obvious reason, "Worldwide Leader in Sports". If ESPN doesn't step up they're televising pickleball or dog shows!!
Why doesn't CBS still televise SEC 2:30 games? Because they got outbid by ESPN. Happens in an open market bid process.
Big10 100% ties to FOX? I think CBS & NBC would take exception to that- $350M ways.
The Big 10 Commissioner (Delaney), it's lawyers, it's media consultants, it's AD's and it's Presidents agreed to the FOX/BTN JV. Not sure you understand business negotiations if you think FOX just steamrolled the deal.
Lastly, I would be VERY surprised if we don't see new players in the upcoming Media Rights negotiations for Big 10, Big 12 then SEC TV rights. ESPN, FOX, NBC & CBS will have to fight off players like: Amazon, Apple, Netflix. Plus with all the acquisitions that Paramount/Skydance has done over last few years, I doubt they will be satisfied with 1 game.
So I am 90% certain the Big 10 will get 2-3x it's existing deal. It's not like that means in 2030 Big10 schools will each make $100M and in 2031 each school will make $250M (2.5x). It means average payments over the contact term. So doubling or tripling means comparing value midpoint vs. midpoint (aka 2027 vs. 2033 amounts).