I think he might show COC later but I do believe next chapter won't be about pure fighting power. The objective is to take the key from Gaban, he's likely going to make a fool out of Luffy in term of mobility. Then either Gaban gets distracted by Nami or a third knight get summoned through the circle in castle to interrupt the confrontation.
Doubt Luffy is going to get that key by normal means, this will be Gaban showcase.
I already said it but Gaban makes me think of Roshi, so would be interesting if he makes Luffy realize he makes too much useless movements since his stamina has been pretty shitty lately