First, let’s start with these facts:
- Caribou heard Shirahoshi is Poseidon when King Neptune was talking to Robin.
- Jinbe captured Caribou, but later Caribou ended up in Udon Prison, Wano.
- Now that Caribou has escaped the Udon Prison, he will tell Kaido about Shirahoshi.
- The general sentiment of the New World is “to survive in the New World, you either join a Yonko or team up to fight one”.
- Caribou was willing to join Luffy’s Crew back in Sabaody, so makes sense he would want to join Kaido.
In Chapter 985 Kaido just announced 2 things:
- New Onigashima Project
- He and Big Mom will find the One Piece, after they get their hands on an Ancient Weapon.
Kaido could be talking about Uranus or Pluton, but with Caribou there it makes sense they would go for Poseidon AKA Shirahoshi and by proxy the Fish-Man Island.
I think that Kaido will soon announce the 1st step to the One Piece, which will be getting Shirahoshi.
This will add even more stakes to the fight, as Jinbe & Luffy are going to get additional motivation to take down Kaido & Big Mom here in Wano.
Big Mom hates Luffy and what better way to show the wrath of a Yonko, destroying Fish-Man Island, since the Island is now under Luffy’s protection.
This also lines up with Madam Shyarly’s prediction of Fish-Man Island being destroyed.