If you have not read the latest chapter of One Piece I highly encourage you to do so before reading the rest of this thread.
This chapter was more dialogue setting up the plan to take down Kaido until Eiichiro Oda throws a massive curve ball and brings Kaido directly to the Straw Hats. The last page of Chapter 921 completely ramps up the pace and we finally see kaido’s devil fruit power fully revealed.
Kaido has Momonosuke’s real zoan type devil fruit power and it is looks POWERFUL. Now we have to ask ourselves the question can Luffy defeat Kaido? Kaido is Yonko and revered to be one of, if not, the strongest pirate alive. He is a man of enormous stature and is so bored of living that he attempts to kill himself for fun. He is also in command of one of the strongest pirate groups in the world, The Bear Pirates. He has many connections around the world and is protected from the government.
No matter which way you look at it this will be the moment where luffy’s title as 5th emperor of the sea will be tested. Luffy has limited allies and did not have to time to gather the other samurai. The sheer power of Kaido’s army is too overwhelming for Luffy currently. Not only that, but the island is isolated from the rest of the world and surrounded by violent weather conditions prohibiting entry and exit. He has already proved that the new generation of pirates is too ahead of themselves; defeating Captain Kidd and making him part of his crew (Not to say Kidd is on the same level of Luffy).
Because of this my theory is that Zou will come to the land of Wano and receive his final order. The only being capable of making it to Wano safely and in a timely matter is Zou. Zou will hear the cries Momonosuke, most likely not Luffy, and playing a role in defeating Kaido.
This is all just speculation and I’d love to know what you think so please leave your thoughts down below and I hope you enjoyed. Take care!