Yeah, this is the main reason why I think that if it's next, it's a combined Vegapunk/Elbaf arc. Go back and see all of the references to Vegapunk and Gigantification, and how that tied to Caesar, Germa, Big Mom, Kaido (the Numbers), etc. It's ridiculous really lol.
I mainly think there is something in between though, some (hopefully) small transition arc that gives us more background on another faction, i.e.
Blackbeard and Hachinosu or Shanks' main island.
Maybe that place reintroduces us to Bonney or Urogue. Maybe that brings Crocodile back finally. Maybe this segues to some major conspiracy with the Underworld and that plotline (which isn't over BTW), and maybe as to who truly runs it beyond the Underworld Emperors. Maybe that leads to Vegapunk/Elbaf.
Maybe all of this leads to the Final War. Like how Punk Hazard not only lead to Dressrosa, but to Zou and culminated to Wano.