WARNING: The following contains spoilers for Chapter #56, “Code,” of Boruto: Naruto Next Generations by Masashi Kishimoto, Mikio Ikemoto, Mari Morimoto and Snir Aharon, now available in English from Viz Media.
When Isshiki Ōtsutsuki revealed the Karma mark on Kawaki's body would rewrite the teen and allow him to reborn, it seemed to answer the mystery of why Kawaki started off the Boruto series as an enemy. That flash-forward showed him as the person who destroyed Konoha, killed Naruto and was gearing up to attack Boruto.
Theorists believed that the process changed and Isshiki's mind was placed in Kawaki's body, which was then used to carry out the alien's bidding. However, when Isshiki died and Kawaki lost his Karma mark in the manga, fans were left to come up with new theories as to why Kawaki would turn evil. Thanks to Chapter #56, another possibility has emerged -- and it's an idea that Kawaki himself posits.
Kawaki wants to cure Boruto of his mark, knowing Momoshiki's consciousness is taking over Naruto's son. They're both 80 percent Ōtsutsuki, but the transformation is much more drastic for Boruto who can be possessed once he uses his powers and drains his chakra. But Kawaki offers up an idea: those who wield the Karma can transfer it to someone else. He insists Boruto track Code down and put it on him so if Momoshiki takes over Boruto's body, or if Boruto dies in battle, he can be reborn in Code.
The problem is, Kawaki doesn't know Isshiki appeared to Code before he died and gave him a White Karma, as opposed to the Black one the boys had. This allows Code to get all of Isshiki's powers but remain himself. It's here that the potential twist for the future lies, because, by Kawaki's logic, Code can also transfer this mark to someone and be reborn. It stands to reason that when Kawaki and Boruto hunt Code down, Code can place this mark on Kawaki instead.
It's also a sneaky way of having the Konoha heroes think they killed the original Code, all the while, his mind can take over Kawaki's body. It'd be perfect revenge, too, as Code revered Isshiki, thus completing the initial project Isshiki started with Kara when he turned Kawaki into this host.
Not only this but it'd also allow for personal vengeance from Code. After all, he always hated that Kawaki was able to take Amado's experimentation and become the Vessel. Code couldn't, which left him jealous. That's why he wants to end Kawaki as soon as possible.
It won't be easy as Code doesn't have to hold back anymore but if he does lose, transferring the Karma would be a great contingency. More so, given that Code is revealed to be more powerful than Isshiki, it'd explain how Kawaki goes on to wreck Konoha in Boruto's future. And so, by him jumping into the perfect body, we'd get the ultimate Vessel -- one that could destroy everything Boruto holds dear.