Gaethje is insanely easy to hit, doesn't have that good of a chin, and happens to be highly regarded at the moment. Conor will finish him inside a round, and it'll set up a super fight with the winner of Masvidal vs Usman, or Khabib vs Tony (which could certainly be Tony, despite everyone writing him off). It would also justify the title shot at 155, so people stop crying over Conor getting a title shot, despite selling more ppv's than any other 10 fighters combined. It'd also probably build on his nice guy persona, since him and Gaethje don't have any bad blood, and Conor would probably be respectful. It's a win/win/win.