Oda planned from the very beginning for each Straw Hat to have a specific part of the end of the journey devoted to them.
- With Sanji, it seems like Oda long ago planned to have a Yonko who was obsessed with food, so that Sanji could have his defining moment as the best chef out there.
- Zoro is based off Oda’s original character Ryuma, the king of the swordsmen. Coming to Wano will bring Zoro’s character full circle and I am certain this will be the arc where Zoro plays a major role in the land of swordsmen.
- Nico Robin will be the one to finally unravel the history of the world, and will be deciphering the final Poneglyphs.
- The ultimate test for a navigator would be finding Laugh Tale. That would be Nami’s key role.
- Franky will be making Pluton, and I am certain of it. Perhaps even converting the Sunny into Pluton. He comes from a long line of shipwrights entrusted with the blueprints to Pluton in case an evil enemy ever acquired the real thing. I am certain either the World Government or the Blackbeard Pirates will be discovering the Pluton in Alabasta, and Franky as the last successor of the Pluton blueprints will have to make a counter ship to combat it, as the line of shipwrights was always destined to do.
- Roger died of an incurable illness. At this point, Luffy has been shaving away his lifespan repeatedly, and I am certain that there will come a point where Chopper will have to tackle his dream of “curing any disease” head on when he has to save Luffy’s life
- Many believe Ussop’s role will be Elbaf, but I think there’s something more to it that would be a little complicated to go into.
- Brook meeting Laboon also ties up a loose end but that’s not the same as playing a key role in the final arcs of the story, and I have more ideas on how Brook will play a part as well that would be complicated to explain…
- Same thing for Jinbe whose dream is is to see Fish-Men and humans coexist peacefully, something that will happen after the Final War.
*Theory by pentothecap