Well maybe they didn't include the Big 12 in their flimsy alliance because each had a plan to break it apart in the near future. You have to remember a conference commissioner has a front row seat in the expansion process. They actually know what is happening unlike the so called Nostradamus's of twitter and youtube world.
Thing is not everyone in remaining 8 will get a seat at the table. Perhaps none of them.
Anything is possible but if the pac expands which they probably will at some point the most logical targets are the big 12 leftovers. Its just which ones and how many.
Why would the acc need to add 2 teams if the pac 12 took 4? The pac 12 has been struggling and adding some big 12 teams would give them a presence in the central time. The big 10 doesn't need to do anything. They will be fine and I don't think they would add anyone for the sake of being at a certain number. I don't see a 2 team option for the acc that would make there product any more desirable.
Simply thinking 'if' those conferences wanted to take in the Big XII teams, they could do so by expanding to 16 teams per conference. I doubt the B1G is interested in doing anything, unless it was a helluva big splash, i.e., like adding USC and Oregon.
PAC is probably next on totem pole to get top teams pilled out and the only one able to do that is Big 10. Big 10 has plenty of options and can afford to sit tight and play waiting game.
The Big 10 doesn't have to do much of a anything. They will always be the main competitor to the sec. What the pac 10 and acc do is of no consequence to them. The acc will more than likely be the next up on the chopping block but that's more than likely a decade down the road. The reason most of the smoke revolves around the pac 12 adding big 12 members because they are the only conference that might benefit from doing it.