We seem to be taking as a given that ND will be a playoff team if it wins out, but I'm not 100% sure of that - if Clemson, Oklahoma and Wisconsin also all win out (unlikely, but possible), are we sure that the committee would rank ND ahead of two of those teams? (In this scenario I'm also assuming that Alabama and GA are undefeated headed into the SEC Champ game, in which case I imagine that both will end up in the playoff.)
Edited to add: For what it's worth (probably not much), 538's Playoff Predictor gives ND only a 26% chance of making the playoff in that scenario, but also gives the loser of the SEC Champ game almost no shot in that scenario, which I don't really agree with/don't think tracks how the committee will approach it.