That would be dope.
Resisting Imu through sheer power of will would be an immense feat.
Black flames
I think it could certainly happen sooner than later as a consequence of CoC Infusion for damage boost and/or PoL for physics-defying qualities like Marco's regenerative flames.
It's very easy for me to picture Sanji engulfing Sommers' vines in flames that do no harm to his crew.
Issue with a flame upgrade is that he just got one last arc so another fire upgrade so soon will kinda invalidate Ifrit.
But then again, Ifrit has a bit of a scientific element to it with it being blue and also being built off of the exo at it's base so if Sanji is gonna be evolving from "Warrior of Science" to "Warrior of Love" I guess an upgrade could be on the cards ^^
Personally with regards to the "impossible" that Sanji will do. My guess is that PoL will allow him to be able to hurt immortals.
We've barely scratched the surface on Sanji's awakening and Ifrit is already becoming more common place.
Similary to Luffy's progression - Diable Jambe became the equivalent of G2 & G3 over the timeskip, and now Ifrit already appears to be settling as Sanji's equivalent to G4.
I generally agree it's too soon for Sanji to upgrade to a new flame colour unless it specifically has something to do with Sanji awakening Conqueror's Haki and applying it to his flames.
Whether that results in a new colour of flames that act as a massive damage multiplier and/or grants physics-defying properties as a consequence of PoL - I'm on board so long it doesn't erase DJ and IJ, and Sanji learns to apply PoL more consistently across the board.
Not gonna lie I’m not really sure how I feel about this ACoC ting. Of course I think it’d be nice for Sanji to have it but not convinced it is the correct route for his development.
The effects of CoC Infusion and/or PoL on Sanji's kicks, flames, exoskeleton, and speed are essentially wide open. Sanji could be capable of unblockable attacks in addition to defending against the impossible.
I could easily picture Sanji obtaining new flames with such absurd qualities they boost his speed on par or even greater than Kizaru. I'd personally dislike that, but I don't think that's off the table for the mfer that can destroy lasers with soccers kicks.
Aside from denying Sanji cutting and ranged techniques, Oda's basically done a flawless job in equipping Sanji with a highly desirable skill set.
In terms of physicals, Sanji is far beyond what is humanly possible. Advanced forms of Haki are the only things that will allow Sanji to leap forward now. I think if the Wings show mastery over CoC Infusion, Oda won't even address how or why when they show off advanced Armament next.