At this point every conference still wants ND more than it needs to join a conference. Further, we know that ND will still be playing USC every year (something USC insisted on as a condition of entry).
The potential deal breaker is if the ACC gets raided and is no longer a viable partner. At that point, ND may need to jump to the Big N to keep a viable football schedule and have a viable home for Olympic sports, but we aren't there yet. Lot's of rumblings about Clemson and FSU going to the SEC, but it is pretty well known that USC (South Carolina) and UF don't want that to happen since it would diminish their standing as the only SEC schools in those states. Also, unlike adding Texas and OU, adding Clemson and FSU just further divvies up the TV deal pie, without adding any new markets.
The super conferences are happening...and eventually there will likely be a Power 4 (instead of the current Power 5), but it will likely be a slow process and the ACC is in better position to withstand the inevitable reshuffling than the Big 12 or Pac 12.