Imagine a scenario where Arizona St wins out from here, defeating BYU, Arizona and Colorado to win the CCG. Could Army (as well as Boise St) finish ahead of the Big 12 champ in such a case if they finished out undefeated (which is highly unlikley obviously)

That would have Army defeating AP #6 Notre Dame, 5-5 UTSA, 7-3 Navy, and then AP #20 Tulane.
Whereas Arizona St would finish out by defeating AP #14 BYU, 4-6 Arizona, and then AP #16 Colorado.

Given that Army is already ahead of ASU in both the AP and CFP rankings, it seems like those last few weeks may not be enough to bump ASU ahead.

Granted, this is substantially less a concern if BYU or Colorado wins the conference, but if ASU gets it, there's a chance we're the #6 conference champ. That scenario at least would mean Notre Dame doesn't make it, so that would open up another at-large spot though.