What if Diable Jambe is CoA based, and Asura is CoO based?
That would explain why neither Sanji and Zoro can use those abilities to their fullest extent, because they don't specialize in those forms of Haki.
Diable Jambe is purely physical, and Luffy can replicate fire based abilities with Red Hawk. This coincides with CoA.
Asura is stated to be an illusion, which is 100 percent mental, which coincides with CoO.
The stronger Sanji's CoA gets the stronger Diable Jambe becomes, and that would mean the stronger Zoro's CoO becomes the stronger and more frequent he can use Asura.
That would be an insane plot twist by Oda.
Please make this happen.