My take is that, much like Oden's own "errant" forecast of events vs. the adjusted timetable framed by Toki's own prophecy, the finale of Wano will be "pushed back" for the foreseeable future. One can't go back in time, but stalling it may be another matter. And although Fate in the One Piece universe may be ultimately set in stone, doesn't mean there isn't room for interpretation…or fucking around with the timetable. Methinks both Toki...and Im...have been doing just that behind the scenes all these years.
But anyway, more to the point, I feel we''ll see the complete resolution of Wano getting "postponed" for a time, as the story veers to other locales and plotlines, essentially tying Wano's conclusion to that of another arc or more ( however long or brief ), simultaneously capping off all involved.
I just honestly don't see Wano playing in the linear, straightforward fashion most seem to think, despite however much Oda seems to be heading in this direction...or trying to convince readers as much. There's a lot more to it, but that'd a dissertation and a half.
But yes, tldr version: Wano isn't ending anytime soon. Next arc(s?) may even coincide with its conclusion, as the focus ( and cast ) temporarily jump to other locations for a spell. Straight up: I see Shiki making his canon return/reintroduction; he's in possession of God Valley, it's his mobile aerial base; he's basically relocating God Valley and possibly more islands directly towards the vicinity of Wano.
Along the way, Vegapunk, the Revolutionaries, Sabo/Vivi, and many more will get swallowed up in the course of events.
The conclusions of this arcs-within-an-arc will segue directly into the Twilight of the Gods…the battle of Ragnarok at Elbaf, which I imagine will encompass a three way battle between Shanks/the Giants, the WG, and Blackbeard. The Strawhats may not be sticking around for this, though; I happen to think Elbaf itself will transition directly into Roadstar ( located somewhere very near Elbaf ) and Laugh Tale directly; two back-to-back full lengths ( Elbaf and a conjoined Roadstar/Laugh Tale I mean ) or one big chunky arc involving all therein.
And that itself will kick of the last major arc of the series, the true final battle; global chaos spurred by Blackbeard revealing the true history ( or at least whatever choice selective bits he deems to dish out, minus much needed context ), leading to mass anarchy, IM, the Gorosei, and the WG losing their shit and resorting to drastic measures, and Teach exploiting everything to unleash his final assault upon the world.
And again, the Strawhats won't be around for the initial salvo; Teach is fuck em over bad at Laugh Tale, temporarily placing them....off teh grid. But then, they might also get the chance to truly one-up Blackbeard and Roger both...by managing to reach one other final destination that even Roger may not have been aware of; similar to how Roadstar itself was mentioned by Roger to be an as-yet undiscovered island, and believed to the true final stop on the Grandline, at the time.
So in summary, basically three major mega-arcs consisting of a series of several arcs, varying in length, some of which proceeding and resolving simultaneously:
Final 3 way global battle: Luffy and allies vs Im and allies vs. Final Boss Blackbeard
Mind you, as some have mentioned, one could say the "Final War" has already begun in earnest in relation to recent events. It's another big reason why I think Wano will drag out longer; by the same token, the events of an extended Wano narrative won't simply further pay out key events pertaining to the Final War, but also begin revealing massive chunks of the True History even before we get to Laugh Tale, thus justifying its already considerable length.
It's all threading together.
So yeah, I'd estimate we're looking at something a little less than a decade's worth of One Piece left to see print. Seven to eight years? Something like that, I dunno.
But as always, it's just speculation, however calculated, on my part.