As long as ND has a possible (even if more difficult) chance at a playoff berth, it wants to stay an independent. Yes, even if excluded from the playoffs at 11-1.
ND and its fans understand that the odds may generally/sometimes/often be against them for this and are ok with it. What 'tho the odds, and all that.
It is fans of other schools who seem to get worked up about it. If ND is excluded at 11-1, I predict there would be very little clamor from ND fans about football joining a conference. Will ND fans be happy ? No. Will they want ND to join a conference? No.
Now, if the 4x16 champs only set up occurs, that shuts the door completely. If there is (legal or structural) ironclad barrier to the playoffs as an independent, ND will be in the ACC for football in ten minutes.