Out of curiosity, what makes you think he’s gonna die? Don’t think I’ve seen anyone say that about him, and he hasn’t made enough of an impact on the storyline for his demise to really resonate with the audience…
There is a reason Weevil was introduced so Late into the Story & left for Final Saga (Post-Wano)
His Story Arc apparently didn't need so much Build Up, indicating that Oda is planning a Meaningful Ending for him
Cuz if he is gonna be there at the end just for sake of Fighting Straw Hats or Allying with them, then it doesn't explain why Oda even bothered creating him in first place
Secondly, just from his Introduction, we know few things:
1. He believes he is Son of Legendary Whitebeard (Fans obviously can see he is not), which means that this Detail was added for his Character Development, not for the sake of Readers. It's him who must learn that He isn't Son of WB, not Audience, which begs the question, how will he react to it?
2. Bakkin is using him for her own gains, and currently She is targeting Luffy, meaning that the difference between Manipulated Weevil & Free Weevil is Fighting Luffy, indicating that Weevil will be a Villain, turned Ally once Bakkin is dealt with
3. He really really hates Blackbeard, which guarantees that there will be an encounter between the Two in the Future. Will Weevil defeat Teach? Ofc not, so Oda is preparing another Development from their Encounter
Finally, there is something that really gives Weevil Mark of Death, it's his Name !!
Teach is Blackbeard & he acquired his Two DFs from Thatch & WB, what do they share in common?
They both had the Name of Real Life Pirate Blackbeard (Edward Thatch)
So it makes perfect sense, that Weevil will also die & be the Third One killed by Blackbeard (Fulfilling his Trion Theme)
This is why Oda made Weevil really Hate Blackbeard & also think he is Son of WB and a Perfect Image of him
Cuz imagine when he finds out that he is not Son of WB, the idea that his existence relies upon, he will basically feel like a "Nobody"
This is where Oda comes in to write a Fulfilling End to this Character, something satisfying for both Final War Characters Spectators & Manga Readers. It's so convenient that the Legendary Pirate he is claiming to be Son of, is actually a Pirate who calls his Crew "Sons" !
So basically Marco at some point will tell Weevil that he can definitely call himself Son of WB & that he would have been proud of him if Alive.
Weevil at the end needs to do something that makes people say this is Son of WB, he definitely reminds us of WB !
Apparently he already has the Strength, but obviously not the Looks & Personality, so let's check WB's Memorable Actions?
There is only one moment that if Weevil recreates, it will remind everyone of Whitebeard & that he is his Legendary Death!
Weevil will do some Last Man Stand & die with a Smile with either him or others saying that He is indeed Son of Legendary Whitebeard! Not only that this would be a suitable end for his Character Development, but his Death is necessary, cuz i believe he ate a Zoan DF & Teach will take it
Everyone is waiting for Teach to eat a Zoan, but something always bothered me, the guy is simply Ugly, if he takes a Zoan from anyone, it will basically look worse, which is kinda disappointing! But what if Teach takes a Zoan from someone even Uglier than him, someone who have Name of Real Life Blackbeard (Just like Teach Previous Victims) & also would have a Meaningful Death that is part of his Character Development. One look at Weevil & you know that this is our Guy
PS: This was only explanation Storywise, i do have Real Evidence for this Theory, but i can't share it, as it is part of my Upcoming Full One Piece Analysis