this brings up something else that factors in heavily - how new conference members are compensated.
The B1G, which has the biggest per school payout (approx 70-80M for original members plus USC and UCLA) has an escalation clause which is not pro rata (i.e., it does not add enough so the new team makes as much as old members). Usually, these additional non-pro rata payments are driven by metrics. Although the media company could agree to pay more, it likely wouldn't in the current environment. I guess Fox is on the hook for the additional amount, perhaps NBC as well, but CBS said their cost was unaffected by adding Oregon and Washington (although their inventory should get better).
The SEC negotiated, in 2020, a contract modification with ESPN so if the SEC takes any new members ESPN has to pay a pro rata share. This modification took effect in 2022. The SEC has the second highest payout, about 60M per year.
The ACC contract is with ESPN. Each school is, I believe, making almost 30M a year. This deal has a non-pro rata escalation so any new additions likely won't get a full share. Schools don't want to lose share, which explains why SMU is willing to go to the ACC with no conference payout for several years. The metrics probably don't give the ACC much of a bump for taking SMU, which is not P5. Cal, and perhaps Stanford, might also have to take a reduced share to join..
The Big 12 is deal 63% owned by ESPN, 37% owned by Fox. The ESPN deal is pro rata escalation for P5 teams. The Fox side is non-pro rata escalation. The Big 12 likely took a small total share haircut by taking the four corner schools (on the Fox piece). The Big 12 paid 31.7M per school before those teams were added, might be a hair under 30M now.
When you look at this you'd have to think ESPN would be afraid of the SEC absorbing a good chunk of the ACC. All of a sudden, what they pay for those schools would go from, say, 30M a year to 60M a year. They would, though, get a GOR buyout up front. But are these schools worth the 60M a year? My guess is that only a couple of them - FSU and Clemson - might be. My guess is that ESPN would balk at a large-scale absorption of the ACC. How would they recoup the 60M they were paying Virginia or Duke? The increment would have to be from the payment to dissolve the GOR - which conceptually appears to say that the schools would be financing their own annual fee increase.
The B!G/Fox would be vastly more likely to have neutral economics for taking a number of ACC leftovers: they would likely only be willing to pay whatever Fox paid the B1G under the non-pro rata escalator. Stanford and Cal would be neutral economically as well, but they would likely attract, say, something like 20M a year from Fox. That is not all that different from what the Pac 12 paid - they may be okay with that. amount.
The problem for the ACC schools other than FSU and Clemson is that they would owe ESPN the value of their media right until 2036. TBH, I doubt those schools have seen marked appreciation in the value of their rights since 2016 with a couple of exceptions. There isn't an incentive to buy it out unless you are gambling the rights value will grow more than most people expect.
This really makes me think Cal and Stanford end up in the B1G and the ACC keeps rolling for a few more years. Obviously, FSU and Clemson are frustrated because they both think they should be at 60M, but it is hard to see how they come out ahead because it is likely to cost as much as whatever increase they get by breaking up the ACC & GOR as they'll get in increased annual fees.