Lol on the sanji part. I would say though, that with cracker probably one of the weakest commanders, I'd say that zoro as he is now could very well be able to pull an upset on a guy like him, but that'd be a very brutal fight and go on for quite long most likely.

And, you have to consider that luffy basically becoming a yonko or modeling one, makes sense because of jinbe. What'll likely happen is his "three commanders" will just be zoro jinbe and sanji (yes I realize this is obvious). That also makes the most sense to the story and shows how and why jinbe is a good fit imo.

But, I will say that, I'd hope you are joking because, as the guy above said luffy will be PK, and close to when he becomes it he should be able to take a yonko. And this means that his three should easily be able to go toe to toe with another's three.

Making it so that sanji at his final strongest stage could take someone like cracker, or more likely someone stronger, as for example many believe, me included, that jack is kaido's 3rd. But I think at the end of the day any guys like that will be what sanji will have to face in the final battle, and I don't think it's insane/unreasonable??