2 vs 1's are extremely unlikely, I just don't really see Oda doing that for some reason.
A series of 1 vs 1's where King and Queen fight someone else (and probably Zoro and Sanji do as well) first is quite likely.
There's also the possibility that we're getting a Worst Gen wankathon Tale of Momo(Luffy)taro, and Zoro, Kid and Law are the Monkey, Pheasant and Dog. In which case I genuinely don't have fucking clue what Sanji would do.
I still think Zoro vs King and Sanji vs Queen just makes the most sense, but I expect Oda to troll a bit beforehand and have other seeming fights before the main one. It wouldn't be the first time he's done that either, remember there was a lot of switching and swapping at EL.