Trust me, 5 years are enought, to end OP without rushing it.
If Oda want to offpanel most fights and only take care for the story, even then it would be still to hard.
We are still in wano and until the next year the flashback would going on, we gonna get also Kaido flashback and I don´t think Wano gonna end until 2021. Alone for Wano we have still many question and plotholes which Oda must fill.
-Oden Flashback(Probably take until the new year)
-The fire festival
-Even around it as with the Navy,Weevil,Marco and Nekomamushi(didn´t still arrive). Alone the Weevil thing is something which we should ask himself, did Luffy really need him as Enemy after he take down Kaido? I don´t think yet im sure Luffy will face Weevil and beat him before Kaido goes down and we most like getting Weevil story aswell.
-We don´t know if the fire festival gonna be a happy end for the strawhats, they can still lose to Big mom and Kaido(if they don´t get helped by the Navy).
-Strawhats alone getting fight panels, more then in Dressrosa when Oda even skipp most fights and end them with one chapter. Im sure one strawhat alone in Wano get at least 2 fight chapters...
-Plotstory around Big mom, do you guys think Luffy gonna defeat both Big mom and Kaido? I don´t think also we have the story whole around Jinbe and the Germa66 which we still don´t know.
-Zoro own flashback(Im sure he getting one) and grow up in this arc overall...
Many other things alone can put in Wano, probably even in 2021 Wano still going continue.
I mean look at Whole Cake island arc alone, something which should get handle at best with 40-50chapters, get at least over 70chapters...
We have Luffy own battle against Kid later in the story, plotstory around the Shichibukai, Vegapunk and also Elbaf(Big mom), new weapon of the Navy getting test... Plotstory around Sabo and co...Shanks crew vs Blackbeard pirates and then the raftel event with the Strawhats vs Blackbeard. And then we most like getting the final arc.
How Oda want to take everything around this in 5years? I would understand if they mean with 5 years that they reaching the final arc of One piece(not the end of the one piece manga). Be honest I don´t think all this could finish in 5years but I respect your opinion about it.
Probably Im just think to negative about these 5years because of the bad ending with I see in Bleach,Naruto,Fairy tail and Nanatsu, I hope Oda could do all of them, but im still skeptical.