I will guarantee you that we make playoffs if we end the season 12-1.
I wouldn't be so sure. Assume the following
Stanford 12-1, Pac 12 champs
Wisconsin 12-1, beats Ohio State in B1G title game
Alabama 12-1, loses to Georgia in SEC title game
Georgia 13-0
Clemson 12-1, ACC Champs
TCU 12-1, Big 12 Champs
Notre Dame 11-1, beat Stanford but lost to Virginia Tech
That debate could come down to Wisconsin with a bad BYU loss vs TCU losing to the team that Wisconsin just beat vs 12-1 Stanford vs 11-1 Notre Dame who beat Stanford but doesn't have a Conference title. Who knows what everyone's SOS would look like beyond that.
This is a highly unlikely, but not unrealistic, scenario.
Bottom line: Too early to make any predictions either way. 12-1 has historically been good enough to get in, but at the end of the day there are 4 slots for anywhere from 4 to 7 teams and there could be a logjam.