I'm actually interested to see whats next.
I don't believe it's Elbaf yet tbh. I still think we are very likely underestimating the number of islands left for the journey. Big and small. It's not really known how deep into the NW Wano is. I do wonder if Oda is following some sort of basic island count between Paradise and the NW.
Paradise had Whiskey Peak, Little Garden, Drum, Alabasta, Jaya, Skypeia, LRLL, Water 7/Enies Lobby, Thriller Bark and Sabaody. 9 or 10 depending if you count Sabaody or not.
As Oda puts it, Amazon Lily, Impel Down and Marineford are side trips, so they don't really count. Thus, if the Final War happens with New Marineford or Mariejois, I wouldn't count those either.
Let's say NW ends with Laugh Tale. You'd have Fishman Island, Punk Hazard, Dressrosa, Zou, WCI, and Wano. That's 6. Now, if we are saying 9 or 10, then its super easy:
- Vegapunk
- Elbaf
- Lodestar
- Laugh Tale
9 if Vegapunk is not included as it's own thing or combined with Elbaf. I think the other 3 are basically guaranteed though, but I'm not convinced Elbaf is exactly next.