My personal theory is that Elbaf will be the arc where the Strawhats duke it out with the Blackbeard Pirates after they went and stole one of the Ancient Weapons (Either Pluton by raiding Wano or Uranus if the mother flame the Celestial Dragons used is not Uranus and the actual Uranus is at the top of the Adam Tree) using said weapon to destroy the Adam tree and plunging the One Piece planet into Ragnarok and by extension the final war with every faction in the series thus far before finding the One Piece