Luffy
Might sound weird but I feel like Oda’s setting up either an observation haki powerup or a Voice of All Things powerup for Luffy
That line where he was the only one able to tell Chopper fell from the Sun World felt like very obvious foreshadowing
Dunno exactly what it’ll be but the setup is there
On top of mastering ACoC to the point where he’s able to pour enough “mass” into his attacks to damage and slow down the regeneration of immortals
———————-
Zoro
Same thing as Luffy as far as ACoC goes. Though for Zoro I’d argue there’s a chance he jumps from “crude” control of his haki straight to sky splitting/immortal damaging
At least in terms of ACoC mastery I wouldn’t be surprised if he caught up to Luffy or came very close. Luffy was able to sky split after a few rounds with Kaido
I don’t see why Zoro shouldn’t be able to do the same or at least come close at this point in the story.
This would more than likely allow him to use KoH infinitely or at least extend the duration significantly
Though there’s an argument that from a narrative perspective it makes more sense to reserve his first sky splitting moment for Mihawk. I wonder what Zoro fans would prefer
———————
Sanji
Unlocking CoC and learning infusion/immortal damaging this arc. Sanji’s much much faster on the uptake than Luffy or Zoro
While you could argue they have greater natural instinct in battle, Sanji’s smarter and is far more self aware than they are
For example, Sanji claims that he knew he had the potential to be a conqueror’s haki user in him while Zoro was actively using infused conqueror’s haki without realizing it and Luffy used the basic version multiple times without even realizing anything had happened
It’s much easier to master something you’re aware of and willing to experiment with