No one else in that conference will be invited to B1G/SEC, and ACC/Pac12 don't offer any significantly different money.

And unless there is some huge drop when those negotiations/contracts come around in 2025, it's unlikely to fall apart at that point either.

There are new bidders coming in to the market as well, like Amazon. It's not just Fox/ESPN anymore.

Pac12 is going to have $$$ problems with their ever-decreasing fan base, and poor performance, and bad time zone. I believe Big12 may actually offer more $$$ per school when the new contracts are done. And that's even if Pac12 is NOT poached for Wash/UCLA/USC by the B1G.