CBS has a 2:30 problem. They're currently booked for both the SEC and the B1G in 2023. They've assured both conferences they'll work it out, but in reality it'll be a lot easier for them if they just terminate their SEC contract a year early and switch entirely to the B1G.
That would give ESPN more leeway to negotiate with both the B12 and the SEC. Getting the Tier1 SEC games a year early would be good for them, and getting those Tier1 games with Texas and OU added is worth even more to them. They could afford to be generous with the B12 in that case.
Fox is going to be the challenge though. They're looking at losing Texas and OU content and not getting anything in return. Not sure how that's going to work out. They can't do anything to block the move or dictate its timing, but they also aren't obliged to make it easier by renegotiating contracts. Either way, Texas and OU are both reported to have the money to pay for the B12 exit, so it's now a matter of the corporate contract attorneys doing their thing.