I agree with that, Who's Who is gonna need a lotta build up for Zoro if he goes that route, I have not been a fan with Oda giving Zoro essential Layups in the New World for whatever reason, he's supposed to be WSS.
As I see it right now, I dont think who's who is strong enough for Zoro, esp IMO i depicted him mastering enma and what hitetsu said about no one before or AFTER being able to tame enma as Zoro > Scabbards, but everyone else has their own interpretations.
I think most sense for Sanji is from your point the Drake disdain for Germa route or the Queen route, i can't picture any other route, also am against Oda using Sanji in NW as a hype tool for enemies, Vergo, Doffy, etc as well.
Right now there are a lot of bridges oda needs to fill/hype, also the Numbers are definitely going to be an integral part, or will they be build up for Luffy, Zoro, Kid, Killer