#4 Hamilton DNFs
With Hamilton currently having one hand essentially on the championship, it would take a real miracle for Vettel to come out with the win. Mercedes have had a fair amount of fortune, with Hamilton's last DNF being in Austria. If he does crash out again in Mexico, for either a mechanical or a racing reason, it would give Vettel the chance he needs to close up the minimum 20 points and keep the championship alive at least until Brazil.
Hamilton does not make mistakes too often, so it is more likely that the Brit will suffer a mechanical failure as he did in Austria this year, and famously in Malaysia in 2016. The championship fight seems like it isn't the most exciting as Hamilton is so close to his 5th world title, however, this sort of outcome would add the right amount of spice as it would give Vettel the chance to close in on Lewis going into Interlagos.