I think you are looking over the ACC academic snobbery. I think Utah and Arizona State are vulnerable if the ACC has a decent gap financially with the next B12 contract. If the ACC can get those 2 and a Texas school to get to 20, it would be great. If the snobbery is in play, I would think TCU is the 3rd team.
If current ACC members depart, I think the snobbery might block Cincy, WV, UCF. I think USF and Tulane get in before any of those 3. I could also see Baylor, assuming Texas Tech and Houston aren't better schools by then. Or even Rice if they become better with the AAC move. Colorado by then might be available as well. And of course the baller move, getting Kansas.
Where these schools are both academically and athletically in 10 years can change drastically. Which makes these scenarios so hard to predict.