According to the 19th opening for One Piece “We Can!” it will be Sanji that will fight Jack.
There is also a black character with no face that Zoro is fighting against, which would confirm that the character that Zoro is fighting, wasn’t shown in manga and anime yet.
My theory is that there is someone stronger than Jack in Kaido’s crew and his opponent will be Zoro.
All these things makes me wonder what bounty must have Kaido, Big Mom and Shanks since their crew members already reach/surpass 1 Billion Bounty.
*Theory by mclovin4000