I think the ACC is much safer than people want to realize. First - if there was an ACC dance partner willing to move with Maryland to the B10, it would have happened. The B10 and SEC both want the same thing in expansion - Virginia and North Carolina. That is where the issues come up.
You have to assume that UVA and VT are tied together in some way. UVA had to pull strings to get VT into the ACC ten years ago. I don't think that the in state politics would allow UVA to leave the ACC and leave VT behind in a crumbling ACC - unless there was a deal for the Hokies to join the SEC at the same time.
Knowing that the second state that both Slive and Delany want is North Carolina - and only want one team from that state, that is where it gets difficult. NC St BOT is under the UNC board. Do you really think that the UNC board is going to allow NC St. leave for the SEC unless UNC has greener pastures to graze? People assume that UNC and Duke want to stay together, and it would be worth adding both schools to one conference. With UNC you have the large alumni base to drive demand for cable network and Duke you have one of the most valuable basketball brands in the nation. However adding Duke by themselves will not drive demand for the cable channel in the state without UNC. So it is all or none in that area. So to expand into North Carolina, someone will have to double down on UNC/Duke - which blocks further expansion unless you want to expand past 16.
Florida State would be a no brainer cable network wise, but what an odd fit geographic wise.
People mention GT - but what value does GT add? Do you think there would be enough demand to watch GT in Atlanta to demand higher prices for the BTN? UGA is the dominate program in the state of Georgia and Atlanta. After UGA, I would rank 5-6 SEC programs with larger fan bases and alumni in the Metro area than Tech. Then you have the last straw for GT - Georgia St. A 40k+ enrollment in downtown Atlanta that is moving up to FBS next year. This will be the 3rd FBS school in the state. The alumni base will eventually (if not already) be larger than GT, and if they can get on a roll like Boise St., they will easily out pace GT in fan support. So why would the B10 or B12 add a school that cannot deliver a market? So take GT off the realignment bandwagon unless they are just a 5th wheel for expansion. No one will pursue them for the sake of pursuing them.
So that is why the ACC is safe, but on soft ground. The schools have to many anchors that prevent expansion by the SEC or B10 from happening easily. The B10 could add UVA, but what school would go with them? The SEC would love to add UNC/Duke - however as has been pointed out many times on this website many times. No school has downgraded the level of academic conference so far in this alignment mess. Even Maryland, Mizzou and TAMU upgraded the academic associate when they changed conferences. No way you can cut the data where you can have the SEC as a better academic conference to the ACC. So unless the ACC is just falling apart, UNC and Duke are off the table for the SEC. The most plausible expansion that I can see for the B10 would be to add UVA and Kansas. The SEC could then add VT and Pittsburgh/FSU. I don't know if those schools add enough value to the cable networks to justify expansion. Which is what this dance is all about.
There is also no reason why the ACC should not have a TV deal on par or greater than the B12. The ACC just picked a really bad time to be average in football. With the media markets up and down the coast - a Cable network, even pennies on the dollar, would be huge money. The ACC is the most undervalued conference. Which is why it makes its members ripe for poaching. However if the ACC can continue to improve the football product - the reward for staying could easily out pace the reward for moving.