I ran over the teams above and below BYU in the CFP rankings to see what path, if any BYU would have to get into the top 12. I started with #5.
A&M: plays LSU, Aub, and Ten; Only possible loss I see there is Auburn but even then I don't think they drop below BYU
FLA: plays LSU, Ken, Ten, and then likely Ala in SEC CCG; I think they win out regular season and lose to Bama. Even then no chance of dropping below BYU
CIN: plays Tulsa x 2 and Temple; Win out or lose to Tulsa once and they're still in NY6 right?
NW: plays Mich St, Minn, Ill, and then likely OH St in CCG; likely wins out regular and loses to OH St. Stays ahead of BYU even with CCG loss
UGA: plays S Car and Van; Unlikely they lose and won't drop below BYU
Miami: plays Wake, UNC, G Tech; Could lose to UNC and would drop below BYU (this would be one place BYU could gain as UNC will lose to ND and won't jump)
OU: plays WV and Baylor; Beat Baylor and likely beats WV. The would likely be in CCG (like Miami could drop below BYU if they lose one game however a loss to Texas in CCG would likely propel Texas ahead of us)
IU: plays Mary, Wisc, Purdue; They have 1-2 possible loses in Mary and Wisc with Wisc being more likely. Loss to Wisc drops them below BYU but Wisc probably jumps.
ISU: plays Tex, WV, and possible CCG; Not really sure what to say about them. I think they likely lose to Texas and drop but then Texas jumps
BYU: Destroys Suck Dog State 100-0
Ore: plays O St, Cal, Wash and then likely USC in CCG; Win out regular season and they jump even with CCG loss. I see no way they don't jump BYU unless Wash upsets them
Wisc: plays IU and Iowa; Both could be in question. Lose 1 and they don't jump. Win two and they do.
Tex: plays Iowa St, K State, Kansas, and possible CCG if they beat Iowa ST; If they win out they jump us. Lose 1 and they don't
USC: plays Colo, UCLA, Wash St, and likely Ore in CCG; Win out and they jump us. Lose one and probably don't
UNC: plays ND, West Carolina, Miami; They're losing to ND and therefore going to be knocked out of it right then. We then want them to beat Miami
Biggest games to keep an eye on: Miami vs UNC, OU vs WVU, IU vs Wisc, ISU vs Texas, ISU vs WV, Ore vs Wash, Big 12 CCG, PAC 12 CCG. The only way I see it happening is with chaos and significant upsets. Or if BYU is able to pad it's resume with more games against quality opponents.