Regardless, this means luffy is near yonkou level soon. He'll have to fight kaidou eventually.
talking about level, I'm not sure Luffy's level is near a yonkou level soon. I mean, he defeated dofla by the assistance of Law, though Luffy was the one who delivered the final blow. I think the same thing would happen against kaidou. It will be 2 (or more) vs 1 (kaidou), not purely one vs one. Just my opinion.