I think everyone is forgetting that the current format guarantees spots for the five highest-ranked conference champions, a 5+7 format (adjusted from a 6+6 format after the demise of the PAC12). That means at least one G5 conference champion will be included. Since most years the top G5 team is not in the top 12 (Liberty was #23 last year), at-large bids will go to teams in the top 11.
I predict this year's playoff will consist of 5 SEC, 4 B1G, 1 ACC, 1 Big12, 1 G5. About the only way the ACC and Big12 get a second team in would be an upset of a Top 5 team in the conference championship game. For example, an undefeated #1 Clemson (remember they start the year playing uga) falls to a #15 10-2 GT (losses to ND & uga) in the ACC Championship Game. In that case, Clemson wouldn't drop out of the Top 11 and would "steal" a spot from the P2.
For us to get an at-large bid, we must beat uga. Losing to uga and the ACCCG gives us a 2-game losing streak at the end of the year against playoff caliber teams, and would provide proof (to the selection committee) that we can't win in the playoff. On the other hand, if we beat uga and lose the ACCCG then we could probably have 1 other loss and be on the borderline of the top 11.