Of course, this is all based on the assumption that ND wins its remaining five games. Otherwise, none of this matters.
Best thing that could happen would be for Stanford to beat Oregon on November 1st. That would drop Oregon to two losses, plus it would help ND's strength of schedule by improving Stanford's record.
In the Pac-12 South - Arizona, Arizona State, and Utah all have only one loss so far, but they all still have to play one another. Best case scenario for ND would be for Arizona State to get its second loss of the season against ND, but defeat Arizona and Utah (giving both of those teams at least two losses).
Kansas State, TCU, and Baylor all have only one loss so far.
Kansas State still has to play Baylor and TCU. Ideal scenario would be if KS State wins one and loses one, which would guarantee that KS State and either Baylor or TCU would have a second loss.
Also, Baylor still has to play both Oklahoma and Oklahoma State. And TCU still has to play West Virginia in Morgantown.
Four teams still have only one loss. Minnesota and Nebraska in the West division (they still have to play each other), and Ohio State and Sparty in the East division (they still have to play each other).
I can't imagine that either Minnesota or Nebraska would win the Big Ten championship, although that would be the best case scenario for ND. But if either one did, I can't imagine that either one would seriously be considered for the playoff.
Both OSU and MSU still have regular season games in Happy Valley. Would be helpful if Penn State beat one or both of them, but seeing that Penn State lost to Michigan, I'm not getting my hopes up.