i deny it because it is obvious , it will make Zoro stronger than Luffy , but the mange is about Luffy and Zoro is his subordinate. Oda will not throw 1040 away just to satisfy the ZKK fans.
Luffy is the main character and he will get the bigges highlights , if Zoro kills Kaido , what is left for main character Luffy to do. since Killing Kaido will be for sure the most impressive thing in this arc. add to that , that Zoro is unconscious , falling , losing blood , already had magic healing , and he himself told that Luffy go that. and the arc is now about to end, BM is already defeated and only Kaido is still standing , and Luffy didn't show anything new beside his advCoC , he didn't even used g4 with combination of advCoC with only one exception as he came back and he went out it after that. i know are of you wants Zoro to slay a dragon but he already did that twice one in PH and King and his fire Dragon , all the symbolic you want is already given there is no need for a third time by the way the Dragon that Ryuma slayed was more similar to that of PH and to King more than to Kaido.