I agree picking up solid non-P5 teams is the most likely outcome for the ACC. It's clear Oregon and Washington want to join the B1G. But if they don't get invited, I could imagine them joining the ACC if the PAC 12 doesn't get a media rights done deal soon.
If the ACC sits around and continues to do nothing in the era of Superconferes, it will die. The SEC will pick off FSU and Clemson. Then the B1G will pick off UNC and UVA.
The rump Pac-12 is still better than the ACC. Even if they can't get into the Big Ten, Washington and Oregon could walk into the Big 12 and become immediate top dogs in a better conference. And if the Big Ten wanted to scavenge the corpse of the ACC, Duke would be the logical partner to UNC which is the obvious biggest prize.