The ACC dynamic is really interesting. I don't ultimately think they can really do too much, simply because their members are too misaligned on long term goals.
No one really seems to know exactly what's included in the ACC grant of rights. I don't see how they can add new schools at their current payout - which seems to be reliably below what the Big-12 has. If the Pac-12 folds you have to imagine the schools that are able will be heading to whomever can provide the most money. Adding in the geographic problems it just doesn't seem reasonable to think the best of the Pac-12 remainders would jump to the ACC simply to avoid having to be in the "truck stop" Big-12. I know a lot of the PAc-12 schools have thumbed their noses at the Big-12 for cultural reasons, but it will likely soften the blow if 4 come over as a group. All-in-all it does not seem reasonable that any PAc-12 schools jump to the ACC unless something major changes.
To entice a move, could the ACC renegotiate a new media deal contingent upon additions? Possibly. They would have to be able to obtain a higher per-school payout than the Big-12 and if they were able to do so that would provide a lot of stability for the next decade or so. The major problem with getting a new deal is exactly what we've just seen in the Pac-12. Where would the money come from? Most potential media partners seem pretty tapped out, and what incentive would ESPN have to renegotiate an already ESPN friendly deal. The truly valuable schools from a media standpoint are already locked in, and how much would UW and OU really add to the pot.
In addition to the problems with actually financing a new deal, if I am an ACC fan at a school that isn't UNC, FSU, Clemson, or Miami I am very concerned about any renegotiations or any other activity that could open any door to breaking a grant of rights. Further, do the above referenced big dog ACC schools even want to renegotiate a deal or expand the ACC? Unless the ACC deal somehow gets restructured for SEC or B1G money I would still think the Big dogs are eyeing a departure as soon as they can afford a buyout. Perhaps those schools would be wiling to renegotiate a deal that keeps things more-or-less pro rata, but wouldn't they want to take some time of the length of the deal in exchange for doing so? There just does not seem to be any scenario where expansion benefits the ACC big dogs without opening the door to another round of alignment closer down the road. The ultimate problem is that unless the ACC gets to B1G or SEC money - they wont - the conference is a ticking time bomb.
I keep thinking it would be interesting to see the ACC add whomever is left from the Pac-12 after more schools depart for the Big-12 in the hopes that whatever remains once the ACC gets picked apart can exist as some form of viable 4th conference. In that scenario a least a little bit of protection is provided to the ACC schools that will get left behind. I don't think its completely crazy to think that a new ACC could somehow operate as a 2 coasts conference where each coast exists as its own separate division. The only problem is that this provides no benefit to the ACC big dogs. If your one of the schools that might get left behind in the next round would you consider agreeing to disband the ACC now or reduce the length of the current grant of rights in able to form a new entity with a remainder of the Pac-12? By doing so you're obviously moving down a step, but you would still be able to form a conference comprised entirely of former power 5 schools. At least arguably, this would be more prestigious than any remaining group of 5 options. This is an option that I don't think can realistically happen, as I don't think most of the schools getting relegated will be able to realistically asses their position, but if you're the Boston Colleges and Washington States of the world isn't this the only real path to avoid the otherwise inevitable relegation to a G5 conference? The overall idea would be to pool the best of the rest of the traditionally power 5 schools rather than letting each fall randomly into the American or Mountain West.
This post ended up being a lot longer than I wanted it to be. The ACC stuff is fun to think about, but there just don't seem to be any moves to realistically be made.