The thing with Arsenal in the cup though is that Wenger can, and will, rotate. Not only does he do it every year - regardless of who else is left in the competition, and what stage they are at - but also, when they have most of their players fit, then their rotation doesn't really change too much. Arsenal have so many options, mainly offensively, that are generally all pretty decent but without being top class. Walcott or Chamberlain. Cazorla or Ozil. Ramsey or Wilshire. Gibbs or Monreal. Does it really matter too much?
Yes Chelsea and City have big enough squads to rotate too, but when they rotate, there is a pretty clear difference between their two sides. Salah is no Hazard.
But hey, it's still nice that Arsenal have at least one more fixture.