The reason Kaido is in Wano is because...
...perhaps, the reason why Kaido is there because it's Wano is because Wano itself is the DF that Gorosei speak about?
The missing 4th animal, the giant turtle that has Wanokuni on its back? Only such thing could be a legend for Gorosei.
Something that hasnt awakened for centuries. However, nothing has awakened now but Momonosuke might awaken it.
Or the reason why it has awakened precisely now is because Zoro just awakened his CoC?!