Regarding Wano's Shocking Ending, everyone are expecting Two Outcomes:
1. ZKK
2. Raid Fails
But i think everyone is forgetting another Very Shocking Scene which is: Kaidou joins Luffy !!
I mean at first the guy was Introduced as this Drunkard 1 v 1 Monster Oni who must be defeated to save Wano & he is so Evil
However as we continue to read more & more, it's pretty clear that Kaidou is on a Mission, he strongly believes in something, he is interested in Joy Boy, he wants to change the World, his First Recruit (King) was saved from being a Guinea Pig so Kaidou words "I want to change the World", suggest he wants to End Oppression !!
I mean someone might say but look at what he has done to Wano, but Yamato asked him same question & he said "This is Wano", implying that He isn't doing this because he is an Evil Pirate, but because it was Necessary for his Mission, for the Greater Good
Also notice how he didn't want to tell Big Mom where Road Poneglyph is, as if he doesn't trust her (That's because he have a Hidden Goal & he doesn't trust Big Mom with it), also each Yonko Crew have a Theme:
WB Pirates ---> They represent Poor People & Orphans, WB gave them a Family & took care of them
BB Pirates ---> They represent Black Sheep in every group, such as Corrupt King, Corrupt Sheriff, Corrupt Warden ... etc
Big Mom Pirates ---> They are basically her Real Family
And finally Kaidou Pirates seem to represent those who are Thrown Away from Society, such as King being a Lunarian or Who's Who being fired from CP-9 or Queen from MADS group ... etc and this same Theme was also included in Donquixote Pirates (Since Joker was intended to be part of Kaidou's Arc).
These Themes are like this because they match the Captain, such as WB was Poor & without Family & Blackbeard was Corrupt Pirate & Big Mom was raised in an Orphanage & Kaidou was treated as a Monster & Experimented on ... etc
I believe that all of these Hints are leading to One Eventual Outcome & that is Kaidou finally realizing that He isn't the one who's gonna change the World, it's Luffy, and the Logical Reaction that Kaidou would have is to give his Respects & decide to leave Wano
Actually this explains why the moment Luffy lost against him, he said "So you're also not Joy Boy"
That's because Kaidou knows that Wano Country needs to be opened so that the World Changes, & he knows Joy Boy will do it, so Kaidou decided to invade Wano & challenge everyone, this way there will be Two Conclusions for him:
Either He is Joy Boy since no one can stop him or the One who defeats him & take over Wano is confirmed as Joy Boy
So for him, it's a Win Win
He also reminds me of Crocodine from Dragon Quest, both seen as Beast Kings, both are very Prideful & wanted a Challenging Fight, and at the end of Crocodine's Fight against Dai, the Second Main Character (Popp) actually intervened & helped Dai & also made Crocodine respect him & realize the improtance of Pride once more. After Dai defeated him & destroyed his Weapon, Crocodine decided to leave with his Army & he later returned in another Arc as an Ally
So what if that's the End of Wano, Luffy is gonna lose once again & Zoro will come to face Kaidou instead, this is the moment when Kaidou shows respect to Zoro as The New Monster Samurai & also learn something new about Pride & why someone like Zoro follows Luffy (I believe that Kaidou will realize Zoro is exactly like him & yet he follows Luffy, which makes him see the bigger idea).
After that Luffy is gonna somehow Unlock his Last Power-Up & defeat Kaido & destroy his Weapon
Luffy + Zoro will make Kaidou change & realize the Answer to what he is looking for.
After that, there are Two Possibilities, either Kaidou accepts his Defeat (Similar to Katakuri) & leaves Wano saying that Luffy is the Promised One & not him, or something happens that makes Kaidou go on a rampage once more & that's when ZKK needs to happen