the loser isn't likely to fall behind BYU (though in a just world tOSU would given they would then have 2 losses).
Perhaps Duke upsets Miami, but probably not. If they do, Miami would fall below BYU.
Possible Oregon slips up at Michigan, but they wouldn't fall behind BYU if they do.
Possible a resurgent Florida upsets Georgia, but #2 UGA isn't falling behind BYU (despite what would be 2 losses).
aTm is the most likely candidate to provide a boost to BYU. Playing at South Carolina, and the Gamecocks should have beaten both LSU and Alabama.
Upsets over ISU or Clemson would help solidify BYU as a top 10 team, but wouldn't move BYU much in the polls.
This is the time of year that unexpected upsets start happening, though.