If Notre Dame does not come on a full football member, and do so rather quickly, the ACC will find itself in trouble, deep trouble. I say that because I do not think that the SEC will stop at 16 members, unless it cannot get the schools it now desires.
The reason I must now accept that the SEC is ready to expand to 20 or even 24 is based in how and what I learned about the SEC's plan to expand to 12 and then play a Conference Championship Game. I am a Tennessee native, and a friend from high school was the son and grandson of UT Vols boosters. They certainly were not the super powerful boosters, but they were well connected.
This friend was part of the media, then working on TV. He called me at just before midnight, all excited. He was thrilled to let me know that he knew something very important about college sports that I did not; he'd just gotten home from a soiree with some of the biggest Tennessee boosters, and other SEC team boosters living near Nashville. He told me about that essentially unknown NCAA rule that would allow a league to play a CCG if it had at least 12 members. He said the SEC would be expanding to 12.
He also told me that the SEC intended to expand to 12 by ruining either the SWC or the ACC. If the SEC decided to go after the SWC, the offer would be made to Texas and A&M, and if either refused to join the SEC, they would make it clear that they would take Arkansas with the one TX school.
He said that if the SEC decided to ruin the ACC, it would offer UNC and UVA, and threaten to take Clemson if one of them would not budge. He also said that the 'Dream Team' pair for the SEC would be Texas and UNC, but that the SEC people knew that they had to go either east or west and use leverage to get anyone they really wanted badly.
My friend and I agreed that the target would be state of TX, because of its size and super abundance of football talent. And so it started, but Texas flat refused to give serious consideration, and A&M balked. The SEC indeed offered Arkansas, and the Hawgs jumped at it ASAP.
By that point, the ACC knew all that had been discussed, and knew that the SEC would not add any other SWC team and so would look to its east side. The ACC prepared not just to defend its 8, but to expand in order to keep pace. JoePa had screwed over northeastern football by going BT. If he had not done so, Gene Corrigan almost certainly would have led the ACC to add 4 schools to match the SEC's planned 12: FSU, PSU, Syracuse, and Pitt. As PSU was off to the midwest, the ACC had to decide between adding 1 or 2 schools, and then which 1 or 2. FSU was agreed upon, and Syracuse would have been the next offer, but the lack of PSU meant that many people felt that Syracuse would not leave BE basketball without having a single old northeastern football rival in its new league. So the ACC decided to go for FSU only.
The SEC also had decided to go for FSU. FSU had been told that it was a matter of formality. The ACC slipped into Tallahassee and won over the administration quickly and then sold Bowden on FSU starting out with total domination over ACC football without being seen as Florida's little brother.
The BT adding PSU was THE reason that the SEC wanted to expand to 12; the CCG was the way to guarantee new money and excitement to cover the loss of some rivalries. The BT added PSU to try to 'own' the northeast for CFB TV dollars. So the SEC was forced to think of new regions for its TV dollar growth. That is the reason that the SEC never gave up on adding the state of TX. That is the reason that the SEC was very happy that the BT stupidly rejected Mizzou to take Maryland and Rutgers: the SEC could get St Louis and Kansas City TV markets.
And that is the reason that the SEC certainly already has a plan to get VA and NC. So if ND does not become a full football member, soon, the SEC almost certainly will offer Clemson and FSU, which would ruin ACC football and thereby make it very easy for the SEC to get into VA and NC.
If ND does not go full ACC football member, then before long ND either will join the BT or join the Super SEC or else get reduced and become BC-midwest.