even after finishing this fight, the wano arc is still gonna last a while i predict till the end of the summer and given oda's breaks
i think this arc's post-battle segment leading up to the next voyage. Will take 10-12 chapters.
several mysteries and subplots pertain to wano/wano arc : Zoro and his lineage, the shinigami thing, the smilie effect, the secret to Wano, Momo's ability to talk to Zunisha, the secret to Onigashima, etc.
on top of that you have potential new crew members, who seem to be getting hinted of joining like Yamato. or perhaps Carrot.
shyt with all this it might take 15 perhaps. Plus theres the fact the SH's might get powerups/upgrades by getting new weapons, abilties, items.