Based on two external factors, I see seeds 6-8 as possibilities for ND, based on the answers to these two questions:
Does Penn State stay ahead of ND in the playoff rankings?
Does Texas beat A&M but then lose to Georgia?
If both answers are yes, then ND is the 8 seed, with a potential quarterfinal matchup against the Big Ten champ in the Rose Bowl.
If one answer is yes and the other no, then ND is the 7 seed, with a potential quarterfinal matchup against the SEC champ in the Sugar Bowl.
If both answers are no, then ND is the 6 seed, with a potential quarterfinal matchup against the ACC champ in either the Fiesta or Peach Bowl.
Does Penn State stay ahead of ND in the playoff rankings?
Does Texas beat A&M but then lose to Georgia?
If both answers are yes, then ND is the 8 seed, with a potential quarterfinal matchup against the Big Ten champ in the Rose Bowl.
If one answer is yes and the other no, then ND is the 7 seed, with a potential quarterfinal matchup against the SEC champ in the Sugar Bowl.
If both answers are no, then ND is the 6 seed, with a potential quarterfinal matchup against the ACC champ in either the Fiesta or Peach Bowl.