Well in the same vein Momo knocking out Kaido would be more symbolic than Luffy doing it.
But then we have to look at theme of manga, the Lore, comparing importance of each character like a character we have been following since day one, character playing second biggest if not the biggest depending on which region you look in making One Piece as popular as it, his dream, context build around wano as a country with legend of Ryuma the dragon slayer of black blade.
And compare that to random perverted kid who first was supposed to be son of Kinnemon but then Oden who turns out to be a random goof ball himself
Well, first off, Zoro's dream is still intact, because it's to be the WSS, not a renowned dragon-slayer. He has also already killed 2 dragons (depending on what you consider King's final attack to be symbolically). And Mihawk existing and not being mentioned at all in an arc so dedicated to samurai should tell you that swordmanship /=/ samurai, because not all swordmans are samurai (Mihawk, Vista) and not all samurai are swordmans (Nekomamushi, the ninjas, Izo). Zoro can still have his big moments when it comes to swordmanship, which is what matters, in future arcs.
Would that still leave the whole Ryuma stuff unaddressed? Depending on how Oda portrays it, yes. But Zoro wouldn't be more of a bad character if he misses this chance as some of you say.
And yeah I don't like Momo that much neither but come on, you have to admit that he is supposed to be shown evolving from perverted scared useless kid to mature responsible brave adult that can rule Wano. It fits.