People have been saying that Elbaf will be the next arc and while I agree that it’s a possibility, I’d like to suggest an alternative that would tie in few plotlines and explain narratively why Marco even is in Wano right now.
Assuming that the Wano arc will have happy ending, like every other kingdom saving arc so far. There should be an end party where things calm down from all the chaos.
The fire festival itself was supposed to be related to respecting the dead so that makes me think that Luffy and Marco will finally meet and have a discussion about Ace. Luffy was never able to tell them the last words of Ace despite Ace asking him to do so. This discussion would quite naturally lead to conversation about Ace’s grave and that Marco knows where it is. Luffy would like to visit.
Thus, instead of Elbaf, I’m thinking that next arc will be a short “in-between sagas” arc about Luffy visiting Ace’s grave. That would explain why Oda even brought Marco into the story in the first place. Sure there’s always been the plot reason of “Marco is strong and we need strong people to help us fighting Kaido”, but that has nothing to do with the actual story of the series.
Marco being the plot device to bring Luffy to Ace’s grave could give us a great moment of Luffy visually accepting his past and overall it would just be a great scene. Then Luffy could go to Elbaf in order to meet Shanks. Perhaps Marco was the one who knew where Elbaf is so that Strawhats could get the directions to get there.
Luffy teaming up with Marco for a moment would also give us finally a tie in with Weevil to enter the story and we’d finally be able to learn: What is his deal!
Theory by Ronthay (https://www.reddit.com/user/Ronthay)
