Here's my take on the whole topic, with one major caveat that might make you uninterested in continuing the conversation.
I am extremely confident that if we finish undefeated and are still playing at a high level that passes the eyeball test, we will be in the playoff. However, here is my caveat...I am far far far less confident that we will actually finish undefeated and still be playing at a high level that passes the eyeball test. There have been so many seasons under Kelly where we looked good early on and then fizzled down the stretch, that it's almost impossible for me to imagine the same thing won't happen again.
Having said that, if we do go undefeated and are still looking the part, I only see one scenario where we don't get in and these are the four it would be in that scenario:
1) Georgia 13-0
2) Tosu 13-0
3) Bama 12-1 (close loss to GA in SEC championship)
4) Clemson 13-0
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5) ND 12-0
I know you think it would be the same result if Bama beat GA close, but I disagree because Bama is the only team that has looked so far and away better than everyone else that they could survive a loss and still get in over a major undefeated. IMO none of the other unbeatens have looked super elite and each of them have actually looked very human at times (especially Tosu). Also, the committee is human and they have seen ND play very close with GA and Clemson in the last couple years, so I don't think they would consider them superior to us enough to get in over us with a loss. Alabama on the other hand looks other worldly right now, and I the last memory of us vs them was a disaster.
End of the day it boils down to this, I know the committee has precepts that they are spos to go by and publicly they will always claim that is what they go by, because that's what they have to say publicly...but once they get behind closed doors I don't think they give a rat's ass about precepts, conference championships, SOS, etc.
They are just going to pick the teams they want, and spin the narrative however they have to in order to make their choice look justified. If we keep playing the way we have been recently, or even start playing better (which as I already said is unlikely in my eyes) then it will be a real easy spin for them to put 12-0 ND in over 12-1 GA, rather than having an instant reply of the SEC championship in "the first round" of the playoff, or an undefeated WVU who is the Champ in a down year in the Big 12 and doesn't play the kind of defense they think matches up well to compete in the playoff.
Ultimately it's all speculation and there is no 'fact' to what any of us say because they can pick whoever they want and we just have to live with it, but with as good as we've looked overall to my eyes and with some of the people you don't normally hear talking high about the Irish, talking high about em now, I think we'll be real high (maybe even #2 or 3) on the committee's list "IF" we are still playing lights out come the end of the season and are sporting a 12-0 record.