I think that in the absence of a truly dominant skater, the judges are much more willing to call it as they see it. Kimmie is very good technically but even with the World title she hasn't proven herself yet. She had a great skate at Worlds. She's had several good skates and some poor to middling ones. She hasn't dominanted.
While she is in the best position of all the contenders, a bright, shining new star can take it all away in a heartbeat. Americans love their Ice Princesses. If Kimmie falls, she will pay for it. She doesn't have a record that will hold her up yet.
That's an interesting historical perspective. I think, though, that in comparison to U.S. ladies who will be at nationals this year, Kimmie
has proved herself dominant, nor do I see any bright new shining star who is in a position to step up if Kimmie falters.
Point-wise, Kimmie's absolute worst performance in more than a year was at Eric Bompard, and she still ended up with 158 points. She fell on the triple Axel (which I don't think she will be attempting at nationals) and made some other mistakes. Otherwise, all of her scores have been in the 170s and above.
In contrast, here are the all-time bests of her challengers:
Alissa Czisny -- 168.32 at Skate Canada last year (her only clean performance ever, I believe)
Katy Taylor -- 164.05 a Four Continents (her only victory at a senior event)
Caroline Zhang -- 162.68 at JGP final (but she's still in juniors)
Rachael Flatt belongs in here somewhere at about the same level, I believe (she has not yet skated in any senior ISU event).
Emily Hughes -- 160.87 at the Olympics (her scores this year have been much lower)
Bebe Liang -- 158.91 at Four Continents.
So in order for Kimmie to lose she would pretty much have to have her worst skate of the season and someone else would have to hit their all-time best.
Could happen, I guess. But IMHO Kimmie is less likely to suffer a meltdown than any of the others in this list.