The whole "last year's conference championship losers all dropped" narrative is also patently false.
Last year's conference championship losers didn't drop. Georgia moved up, because they beat #2 Texas and won the SEC. The at-large teams had to shift to accommodate the upset. ND was the #2 at-large at the time, behind Penn State. Since Texas lost, they went from the perceived conference winner to the at-large group and became the #1 at large, which pushed everybody back one.
The only real exception was SMU, as they were ranked as the perceived ACC title winner. When they lost to #18 Clemson, they reverted to being just another at-large team.
The projected losing teams of both consequential conference title games are both currently at-large teams, so their status doesn't change. If BYU loses, they're still projected to finish where they're at, and the same with Alabama, because you can't punish a team for losing in the CCG.
Now, should Alabama win, they'd move up, because they won the SEC. They'd shoot past Georgia, Ole Miss and even Oklahoma, whom they lost to, because they would replace Georgia as the projected SEC winner.
The CFP essentially has teams placed into 2 groups, conference #1's and at-larges. If a team that was projected as an at-large wins their conference, their status changes, as does the team that was in the conference #1 spot.
The same situation exists with BYU. Right now, they're considered an at-large. If they lose, they stay that way and don't move. If they win, however, their status changes to conference winner and then their ranking is adjusted to accommodate that.