Its not as doubtful as one thinks.
Say MSU beats Texas A&M, Texas A&M beats Alabama, and Alabama beats MSU. All three finish with 11-1, 7-1 records. Alabama wins the tiebreaker and beats whoever from the East.
Oklahoma and Oregon drop games late - say Oklahoma State or Baylor beats OU and USC/UCLA beats Oregon in the Pac 12 championship game.
The way the polls work, A&M would probably move up to 3, and 4 would be an open battle between MSU, Oklahoma and Oregon, none of which won their conference. MSU's only loss to #1 Alabama, and Okies and Oregon lost to lower ranked teams.