The fact that already 2years ago almost 3, Shimizu knew how the end of Wano will be surprising.
The fact that Oda in an interview 3 years ago said that he didnt want to finish Kaido just with pouching (which is Luffy way of fighting) tell me that there is someone or something that will end this fight that aint Luffy.
A suprising ending doesnt include the classical Luffy super pounch move and everyone is safe, nah that the standard way to close an arc. So to the one that are pushing ZKK, this could be the surprise that Oda want to drive to close this arc.