Law and Kid aren't on Luffy level and they won't be his level post Wano but that doesn't stop them from being the same level of pirates as Luffy. If they aren't considered among the great pirates after Wano, then either they won't do anything worthy of being a great pirate or there will be some doctoring of information.
As for Zoro, Luffy can just stand there and let Zoro kill Kaido in the next chapter but he'll never get to overshadow or equal Luffy in infamy. As long as he works under Luffy, anything he does will be considered an accomplishment of a SH pirate.