I don't mean to get all cloak-and-dagger, but is there something the B10 and/or SEC could do to hasten either the BigXII or ACC's downfall?
If we had 4 "P5" conferences, all of this would be moot.
As I've said in the past, the SEC and B10 are safe, due to health. The PAC is safe due to geography. But on a long-enough timeline, both the XII and the ACC won't last. I believe the ACC is the stronger of the two, and a conference comprised of the best from both would be legit. ND's tie with the ACC only makes me more certain they'll outlast the XII.
With 4 big-boy conferences, you'd be able to alternate which conference you played OOC, you could sign 5-year agreements, stuff like that.
Anyway, if I was a person in power in college football, I would explore getting the XII and ACC to clash sooner rather than later, because if one sort of slowly dies over time, it will drag everything down for a spell.
I'm not sure how it will ultimately come about because the newer and more complex conference contracts make it more complicated than it used to be but I think that in the long run the B12 will die and ND will more-than-likely be forced to join the ACC more completely.
On the issue of Notre Dame:
It would probably be good for both the Irish and the ACC if they came up with some kind of arrangement where Notre Dame could replace the weaker divisional champion in certain circumstances. Notre Dame's experience this year may have made this more clear to all involved. They ended up fine because they were undefeated but it seems pretty obvious that a one-loss Notre Dame would have been on the outside looking in. Meanwhile, playing a bad Pitt team in the ACC Championship didn't hurt Clemson this year because they were undefeated but if they had needed a quality win in the CG, they wouldn't have been able to get it.
Notre Dame played five ACC schools this year (Wake, VaTech, Pitt, FSU, Syracuse). Maybe they and the ACC will increase that to six per year and allow the Irish to replace the weaker divisional champion anytime their record vs ACC teams is better than the weaker divisional Champion by a set amount. That would have made the ACCCG a much higher rated game this year as it would effectively have been a NC quarter-final. I understand that it would have hurt the ACC/ND this year because it would likely have knocked one of them out of the CFP but they can figure out as I can that situations will be different in different years.
On the issue of the B12:
I still think that 14 is just not the right number of teams for a conference. When
@847badgerfan and others say "go back to 11" or "go back to 10", I get where they are coming from. At the same time, we all know that isn't going to happen. The PAC already tried to expand to 16 and my assumption is that the B1G, ACC, and SEC are thinking the same thing. I think OU/TX to the B1G might happen but it is more likely that they will end up in either the PAC or SEC, probably the PAC. Then the SEC and B1G will probably grab two each out of the B12/ACC and the remnants of the ACC and B12 will be effectively forced to merge and we'll have our four super-conferences.