Theory Theory no mi: kuina returns in one piece world

Kuina, Zoro's childhood rival who died falling down the steps, is actually not dead. Her death was faked, and she was abducted by the World Government and made into an assassin. Kuina stood out and made a good candidate for this because of her proficient

sWordsmanship at such a young age. 

A similar occurrence has occurred in the story regarding, Rob Lucci, who became an assassin for the World Government (CP9) at a young age because of his advanced use of martial arts. With Rob Lucci now being apart of CPO, we expect him to also come with  a power boost since we last saw him in battle. But also with the introduction of the new agency, CPO, we will also be introduced to new characters, such as Kuina who may or may not be going be a secret/different name or identity upon her revealing.

Interestingly enough, Il do not think that her appearance would just be arbitrary. I think Oda might attempt to surprise us with sudden news in the One Piece world that Mihawk has not only been defeated, but has been assassinated. Whatever reason the world government has to assassinate Mihawk will revolve around their dealings with Shanks, maybe after a dispute.

This news would become known after the end of Wano Arc, and will be coupled together with the results of the Marines' plan to capture

the Warlords and dismantle the Warlord System. Because Mihawk resides in isolation, litle details about the event will be known except from what is told by his only companion, Perona. Suspicion

will rise from some of the Marines towards The World Government because they will not know how he managed to die before a plan was set in place to capture him. 

Zoro will begin to go into a depressed state after being unsure about if he can fulfill his dream only to find out after a later encounter with

CPO, that not only is Kuina alive but she is the one responsible for killing Mihawk.

Kuina as well as others in CPO will have great martial arts/powers and very competitive haki control compared to the Straw Hats at the time of their encounter. Kuina will not have better swordsmanship than Mihawk per se, but her skill will be enough especially because she has good haki and is paired with a decent grade sword that has consumed some devil fruit.

Zoro will become one of the first Straw Hats to accomplish his dream after defeating Kuina and avenging his master Mihawk. He will realize the grueling irony that in his journey to become the best

swordsman, after all this time spent to honor Kuina, he still must beat her in a duel, to accomplish his goal, resulting in her real death. 

This will also be what makes Zoro laugh at Laughtale, however this will be a laugh because of the irony in finalizing his dream, not a laugh of joy.