The fact that ND is a national brand even after a long streak lacking success pretty much leaves this analogy dead in the water.
Right now, the idea of Florida State and Clemson joining the Big 12 is pretty exciting. The football playoff system that is evolving appears to be the key to them joining, because the ACC may have trouble getting teams in the playoff compared to the SEC, Big 10, Pac 12, and Big 12. Nobody can say what could happen in the future, say if the SEC asked them to join. But who knows if the SEC will stay on top forever. What if Saban moves on? What if Miles moves on? Anyway, Florida State and Clemson would get us to 12 for now, and that is important in light of what the other major conferences are doing. If the Big 12 goes to 14 in the future, Louisville would be great because it would tie the eastern teams to the west, and of course they are very interested in joining. Notre Dame? If they would join as a full member in all sports, it would be a real coup for the conference. If not, my personal preference is BYU, even though geographically a conference strung out from Tallahassee to Provo would not seem to make much sense. If not BYU, Georgia Tech would be my next choice. TV-market-wise, Georgia Tech would really help the conference.