Based on Luffy's training progression of chapter 955, we can safely assume that Luffy will make new progress if it comes to his fighting capabilities, as in every arc previously.
Since the New World, Luffy has focussed on developing his Haki and his Gear 4 form(s).
Will it end now? What will be new?
Here you discuss and speculate about Luffy's future fighting techniques!
Let me go ahead:
I think Luffy will adapt his Gear 4th techniques to apply Ryou and become more impactful and more variable.
At the best a new and final Gear 4th form might result out of it.
Since the New World, Luffy has focussed on developing his Haki and his Gear 4 form(s).
Will it end now? What will be new?
Here you discuss and speculate about Luffy's future fighting techniques!
Let me go ahead:
I think Luffy will adapt his Gear 4th techniques to apply Ryou and become more impactful and more variable.
At the best a new and final Gear 4th form might result out of it.