So now that Miami has accepted, the 12 team is inevitable, it might take a couple years but there will eventually be one. So lets take a look at the current contenders:
ECU? Man, I couldn't help but laugh when I read about them trying to pull some political clout to get in the conference. ECU offers absolutely nothing to the ACC. Lets see, no expanded tv area, 3rd rate football program, 5th rate basketball program... yeah, don't think that's gonna happen. They best arguement they can come up with is that they have rabid fans... On top of that, all the other schools hate the fact that the North Carolina schools dominate the league, do you really think they would be wiling to add another one? It will be a cold, cold day in hell when ECU is a part of the ACC.
South Carolina.... they don't really offer anything to conference but they are certainly more viable then ECU. However, South Carolina was once a part of the ACC and I'm not sure if they would be willing to join again, even if invited. I certainly wouldn't mind seeing them added though, as it would keep the conference in the Southeast and keep the rivals together.
Notre Dame is all just rumors right now. I really hope this is a serious possibility though. It would definitely make the ACC the best conference in all the land. I'm waiting on this one with my fingers crossed. I could stand adding a non-Southeast team if it was someone like ND.
Realistically though... I think the ACC will add either BC or Syracuse on the down the road. Miami will push hard for either of these two and most of the league was ready to accept them anyways so either one is certainly a possibility.
I just really hope everyone keeps their heads on straight and doesn't let ECU become anything more than wishful thinking from their fans. We already have one chicken shit school with rabid fans (Clemson

) and definitely don't need another.