then in ranking between ND and Michigan I would assume the "comparable" criteria of the Playoff Selection Committee Protocol would apply:
2. Principles. The committee will select the teams using a process that distinguishes among otherwise comparable teams by considering:
Conference championships won,
Strength of schedule,
Head-to-head competition,
Comparative outcomes of common opponents (without incenting margin of victory), and,
Other relevant factors such as key injuries that may have affected a team's performance during the season or likely will affect its postseason performance.
Assuming neither team has a "key" injury before final selection, then Michigan has a championship and ND has head-to-head. So strength of schedule and common opponents could decide it. Well, there will be a common opponent, played at that opponent. The hypothetical one ND loss better not be to NW and I suggest that Brian Kelly put his 1-point-win-is-good-enough spiel aside come Saturday.
Link: https://collegefootballplayoff.com/sports/2016/10/24/selection-committee-protocol.aspx