With Blackbeard having a Logia Devil Fruit (Yami Yami no Mi), said to be the “most evil devil fruit” possessing power to negate other Devil Fruits and Paramecia Devil Fruit (Gura Gura no Mi), said to be the strongest of its kind possessing power to destroy the World, all he now needs is a Zoan Devil Fruit. And it just so happens we recently got a reveal of a super rare Mythical Zoan, whose name was erased from history and which was said to possess “the most ridiculous power”.
Blackbeard will negate Luffy’s Devil Fruit Powers by stealing his Hito Hito no Mi, Model: Nika, completing his Trinity of Devil Fruits and killing Luffy in the process. Okay, Luffy doesn’t have to die but I want to include another idea which fits so perfectly with this one. It’s a Chekov’s Gun waiting to be fired ever since Dresrossa.
Power of Ope Ope no Mi – Immortality Surgery
The translation of “Immortality Surgery” varies and as such its meaning is up for a debate. I don’t think it will make Luffy immortal but rather transfer the remaining life span from Law to Luffy. They are approximately the same age.
“Chekhov’s gun is a dramatic principle that suggests that details within a story or play will contribute to the overall narrative. This encourages writers to not make false promises in their narrative by including extemporaneous details that will not ultimately pay off by the last act, chapter, or conclusion.”
Law is basically living on a “borrowed time”. He was meant to die on Dressrosa and was fully expecting to do so but Luffy intervened and saved his life. Much like what Luffy did to Robin on Alabasta he did to Law and now he owes his life to Luffy. His plan to kill Kaido from the very beginning was just a ruse to kill Doflamingo for what he did to Corazon yet he is currently in Wano, with Luffy and the Pirate-Ninja-Samurai-Mink alliance fighting not one Yonko like the original plan was but two. So Law really had no reason or motive of his own to be in Wano other than feeling obligated for what Luffy did for him, but now he got a reason to move forward.
Law wants to learn about the meaning of D. He wants to learn what his name represents and to do that he needs to find Laugh Tale. He now has reinvigorated motivation to keep pushing forward and he will learn the meaning behind his name after the Straw Hats reach Laugh Tale and find One Piece. This will cause the Biggest War the World has ever seen to erupt, rallying every Straw Hat ally, including Law, to fight the World Government and Blackbeard. This is where Luffy will have his Devil Fruits powers taken away by Teach.
Inspired by what he learned from Laugh Tale, about the D. and its checkered fate, Law will realize what he must do – Forfeit his own life to save Luffy. Law already once operated on Luffy, saving his life in the process and now he will do it again. He is extremely popular character ranking 5th on the global popularity poll and his death is the perfect tragic event necessary to elevate the stakes of the Final War akin to what Ace’s death did for Marineford. Law tragically sacrificing himself to save Luffy and fulfilling the meaning of his “Checkered Fate”, allowing Luffy to defeat Blackbeard and the World Government is the fitting finale for him, and of course, he does it with a smile on his face.
The Symbolism of Luffy Losing His Powers
Stripping Luffy of his Devil Fruit powers would symbolically represent stripping God (Sun God Nika) of its powers, which is a very common trope both in fiction in general and in One Piece. Whereas Luffy once possessed the Human Human Fruit, Model: Nika, The Sun God Fruit, he will be left just as regular Human (Human). He will be humbled and forced to achieve victory through his sheer Willpower alone, proving Kaido’s statement to be true and proving that it’s not the fruit that makes the man but rather the man that makes the fruit (as now, Blackbeard will be one using Luffy’s fruit). It’s not the fruit that makes Luffy the freest man in the seas that brings joy to people around him, it’s just Luffy being himself who does it.
*Theory by The_Biggest_Wheel