Can't see Sanji fighting Lafitte
I think it's very likely we're going to see specific roles 1v1 each other
So, for instance
Captain vs Captain
Navigator vs Navigator
Doctor vs Doctor etc.
We don't know specific roles for most of their crew but we can already say:
Lafitte's the BBP's Navigator. He's probably fighting Nami.
Doc Q and Stronger will fight Chopper
Teach will obviously be fighting Luffy
Augur will obviously be fighting Usopp
I would also wager good money that Devon and Robin will fight each other which leaves a mix of:
Burgess, Pizarro, Wolf, Vasco, Kuzan and Shiliew vs Jinbe, Franky, Brook, Zoro and Sanji (+1 more strawhat to even the numbers)
Again just looking at similarities I expect the most likely matchup for Burgess is Franky or Jinbe and the most likely match for Vasco is the other one
Which leaves Brook and one other person to fight Wolf and Pizarro
The way I see it, right now,
Zoro fights whoever is stronger between Kuzan and Shiliew, Sanji fights the weakest of the two.
I am however also a big fan of the idea that it's a 2v2 - it would be weird for Sanji to fight a swordsman, and it would be weird for Zoro to fight an opponent where CoO is integral to their defeat. That being said it's possible Shiliew can defeat Mihawk before Zoro does and Shiliew has Sanji's dream devil fruit, so both wings of the future PK have a grudge against Shiliew. So it makes sense they both fight him, but that would be too easy, so... Kuzan.