the ACC doesn't have any leverage to force ND to join.I can see the ACC forcing Notre Dame to fully join, and adding West Virginia (or Houston). This would put them at 16, and give them a stand alone conference structure which should hold its own. This creates 3 set conferences. I think you have to push to blow up the Big12, and take what you want from it in order to create the 4th conference.
If that happens I think Texas, Oklahoma, UCLA, and USC end up worse off (NTTAWWT)
I don't think ND will ever join the ACC as full member, but the best possibility for it happen is to get Penn State or another blue blood to commit to join the ACC on condition Notre Dame does so.