If it wasn't already clear, it's clear now-a non-Power 5 school has virtually no chance of winning a national championship. The key for a non-Power 5 school is to try to get into a Power 5 conference. Utah complained loudly after they went undefeated in 2004 that a minor conference school couldn't win a national championship-they eventually made it into the Pac 12. The only slim chance a non-Power 5 school has is to get a really good Power 5 school on the schedule and beat them and win all their other games, and then maybe they have a chance to get in the playoff. It would have been interesting to see if Houston could have managed it in 2016-after they beat Oklahoma the first game of the season, there was much talk of them possibly having a chance to do it, but that went out the window when they lost to Navy in game 6. UCF had a game with Georgia Tech canceled due to Hurricane Irma, but even if they had played that game and won, it's doubtful that would have helped them much-Georgia Tech finished 5-6.
Although it seems clear that Frost would have stayed at UCF next year if the Nebraska job hadn't come open, I think he would have left at some point-as much as he liked coaching there, the reality of not being able to win a national championship would have weighed on him eventually.