@Ghidorah:
You betcha. With the focus possibly shifting to other locations throughout…and possibly another mid-length/mini arc(s) being initiated, with its own resolution coinciding with that of Wano. Very atypical narrative structure, but one that'd allow Oda to more efficiently nip multiple storylines in the bud in one go.
Basically, Shiki's coming back, and the Strawhats are gonna have to deal with him ontop of everything. His return would also tie to the encroaching Final War, which has arguably already started. And the Rocks, Captain Rocks themselves, Blackbeard, Vegapunk, the Revolutionaries, Germa, the SSG...with Kaido, Toki, and Wano's backstory set to present a deep dive and revealing insight into the history of the One Piece world world at large.
As alluded to by Sengoku ( and by extension Oda himself ), Wano is indeed the center point for a great many things. Hence, the "bloated" length and meticulous setup; there's still a lot left to unpack, but it will ultimately line up many ducks in a row for the final phase of the One Piece journey.
So yes, however it goes, expect an extra year or thereabouts of Wano itself at bare minimum, imo. But like I said, anyone concerned w/ Wano fatigue need not worry, as there'd likely be a crapload of other places, people, and locales receiving focus all throughout....and a shitload of awesome developments to come.
But again, that's just my heavily calculated speculation. I'm not going to argue the issue, or claim it's sure to happen. We'll see soon enough what'll happen in print, won't we?
Most or all of the Strawhats are getting captured, tortured in Wano's own underground version of Impel Down ( where Black Mariah was born, and King presides ), with some possibly being scattered or relocated elsewhere ( Luffy becoming Kaido's new personal "project" ). More or less part of what I see transpiring.
One or a few Strawhats may eventually escape Wano and follow in the Scabbards' footsteps ( blatant parallel ) in searching for allies to come help...something Luffy and Co. should've thought to do before embarking on a mission to take on a Yonko. In that sense, they've committed the same error as Oden and Co. way back in the day, which is the point. So it's time for a course correction following a harsh lesson in falling to hubris.
In turn, I suspect this is how the Strawhat Grandfleet finally enters the picture at some point...it's now the Strawhats turn to step up and ask for help, just as Luffy has prompted from both Vivi and Momo in the past.
C'est the vida
I won't splurge into thesis-level detail, but just think of it as a metaphorical reclamation of the childhoods that were "lost," to various degrees. Maybe I'm getting far too ahead of myself here, but I'll just say I think we''ll be seeing Oda exploring this theme in some length not just through the lens of Momo and Yamato, but other characters such as Big Mom and Hiyori...all falling under the umbrella of the greater over-arching themes of returning to the past/starting point, reclaiming the past, turning back the clock, cycles, second chances.....the list goes on; Oda's juggling a confounding number of thematic plates.
The theme of miracles and wish-granting will also be a major thing as we approach the true finale...particularly as it pertains to the legends of wish-granting dragons. That's all I'll say on that front.
Anyways, as to the exact method of Momo and Yamato getting de-aged, without going into full detail as to the plot-related why's, it remains to be seen, but my initial guess is that Bonney will enter the stage at some point as several plotlines begin to converge in Wano, and thereby have a hand in things. That, or as I alluded to before, it could fall under the umbrella of several "miraculous" things going down by Wano's end.
Yeah this is like full blown fanfiction and not likely to happen. The amount of detail in this already is setting yourself up to be pretty wrong in this prediction.
I'm leaning towards Wano concluding much sooner than later. Plus there's really no indication things are about to go on for even longer.