Probably...but maybe not in the way most expect?
In a way, the "afterlife" is already a part of the story. More in the form of "reincarnation" than in a place your soul goes after death. "Souls", at least, are playing a big part in the story. With Brook's Soul King powers, and Vegapunk's multiple bodies, and Kuma's Buccanneer powers letting him still move around after "death".
And a part of me is still wondering if Luffy has reincarnated multiple times already. Thus making the prototypes Romance Dawn versions 1 and 2 both canon to the main story. Oda has been slowly more and more of his old stories from Wanted canon. With Ryuma being canon for a long time now. And Gill Bastar recently being confirmed as part of the Rocks Pirates. It wouldn't surprise me if Oda used "reincarnation" to make Romance Dawn v1 and v2 both canon.
I do wonder if One Piece will end up having a more "science fiction" style afterlife, though. As opposed to a "mystical" afterlife. Brook has said that his soul "returned from the Underworld" (Chapter 443). But, that's a part of his Devil Fruit power. And, if we assume that Devil Fruits are actually a form of Ancient Advanced Technology like some speculate, that could mean the "Underworld" is some Ancient Advanced piece of technology, too. More of a advanced database or supercomputer that stores the data of everyone's memories and genetics, and allows them to be reborn anew in new bodies. Or something along those lines.
And we have seen hints that One Piece is eventually going to go more "sci-fi" in the future. All the references to space and other planets, like the Gorosei's names. Enel on the Moon. Vegapunk being able to replicate most of the Ancient Technology, including most Devil Fruit powers. All of this seems to be hinting that most everything we've seen is actually the result of Ancient Technology, not magic. Which would likely also include a "Underworld". The Underworld is real and they made it of iron and silicon!
Brook also might have been talking literally. Because we do have plenty of hints that the "Underworld" is a literal, physical location. It's likely the hollowed-out center of the planet, where the First World was mining the Forbidden Sun from the Chapter 1138 Mural. Removing the Forbidden Sun likely turned the center of the planet into a frozen wasteland, as hinted by Brook and V Nusjuro's icy "underworld" powers.
So, eventually, I suspect that the Strawhats are going to have to make a journey into the center of the planet, in order to visit this "Underworld". And likely they're going to have to do something to end the endless cycle of reincarnation. Like a literal version of the goal of Buddhism. Which would put us in opposition to Blackbeard, who seems to want "Dreams to never die". Luffy and Joyboy's side wants things to "grow", and Blackbeard and Rocks' side wants "consistency". One's a spiral, the other is a circle. Similar, but different.
Zoro's role, as the "King of Hell", would probably be to defeat the "Grim Reaper". AKA a holographic AI program designed to keep this Ancient Technology running forever. Or something like that. Think of it kind of like various versions of Lim from the One Piece Odyssey video game. Zoro has to cut something uncuttable, and conquer "death". Which feels more or less fitting.
https://onepiece.fandom.com/wiki/Lim
I'll admit this is all...a weird scenario. But, I could see things eventually making this turn. The "afterlife" is likely real. But, like with most things in One Piece, it's probably also going to turn out to be some form of Ancient Technology run amok. That's my personal bet, anyway.
