This is the topic where my expectations are completely at odds with most other Zoro fans.
Yes, Zoro and Mihawk will deal with each other at the same time as Luffy meets Shanks. And him and Zoro, if they ever are to fight, which is no guarantee, will do it before Laugh Tale.
One of the main purposes- arguably the main purpose- of the abolition of the Warlords plot is that it kicks Mihawk into action. It‘s Oda’s excuse of moving him from stagnant Paradise character waiting in the wings to effecting the plot in the New World.
The time that it has happened is deliberate. It comes during Wano. We saw, going into Wano, that Shanks was preparing to finally meet Luffy. After Wano, who’s going to be one of the main figures in the news- Zoro, for his role in defeating Kaido.
Zoro and Luffy are the only two people that really interest Mihawk. Zoro, for obvious reasons, but his interest in Luffy as well can’t be ignored. Mihawk went out of his way to hunt him in Marineford. He went to the Warlord meeting (which he apparently never bothered to do) because Zoro and Luffy would be talked about. And the big one, when Mihawk met Luffy in East Blue he went out of his way to go to the NW and talk to Shanks about him. Not to tell him about Zoro, but to talk about Luffy, because Mihawk knows what Luffy means to Shanks.
So, Mihawk’s being hunted. He’s quite enjoying it. Probably sinks a few battleships for fun. Then he gets a News Coo where the headline news is “Emperors Toppled! Strawhat Pirates New Force in the World!” With a big picture of Luffy and Zoro front and centre.
Now, if Mihawk wants to fight Zoro- and he does- and he wants to see what Luffy can do- and he does- then why wouldn’t he go meet up with Shanks? He clearly knows about the promise between Shanks and Luffy to meet again. Instead of running around by himself trying to find one ship in a wide sea, why not go meet up with his friend who is guaranteed to run into Luffy and Zoro in the near future? It’s by far the smartest way to go about it. And Mihawk and Shanks can talk about the big changes in the world while they’re at it.
It’s a nice, neat way for Oda to tie up characters who have clear bonds together up into a bow. Certainly a much neater way of dealing with things than how he’s tried to squash Big Mom into Wano.
As for what it it means for Zoro and when he becomes WSS, well, you just have to get prepared for the fact his final fight is not Mihawk. Just doesn’t work, and hasn’t for a long time, Mihawk is not a villain, in the final war where the fate of mankind is on the line with Luffy the only one who can save everyone, you can’t have his right hand men, strongest subordinate, Strawhat who has been with him the longest time... fighting his friendly mentor figure in a duel that has absolutely no stakes in a global level whatsoever. It just does not work in any respect. And if you think Zoro is fighting Mihawk after the final war, again, you are deluding yourself. Luffy is getting the final fight in the series, no one else. It’s his story, after all.
And as an aside, Shiryu killing Mihawk makes sense to me. Folk may not like it, but it makes sense. If Oda is willing to off Shanks to Blackbeard, he’ll be willing to off Mihawk to Shiryu. That way Zoro’s final fight can be for the WSS title, and it can be to, basically, save the world. “He can’t do that, we’ve been waiting for this fight for over twenty years!”, you say. “Yes, but we’ve been waiting for Luffy to return his hat to Shanks since the very first chapter and I‘m not sure Oda’s going to go through with that either”, I reply.
I understand the worry- “if Shiryu beats Mihawk then Mihawk is weaker than I thought.” Nope, it means Shiryu is stronger than you thought. It does not take a great deal of time to set up that a character is really strong. Just look at Katakuri and Oden as recent examples. A good flashback of Shanks vs Mihawk (feat commentary from WSM Edward Newgate), some modern day feats (I very much suspect that Kid and Killer will continue their purpose in the series as being “Luffy and Zoro, but shitter” and get destroyed if they try and go up against the two) and a few well placed character statements hyping up Shanks and Mihawk, and the two are firmly established as bonafide top tiers regardless of their eventual fates. Prior to Blackbeard and Shiryu arriving to steal the show. Then the same process happens for those two, good flashback, good feats, other characters hype them up and it’s still made clear that everyone is really strong and a worthy final opponent for Luffy and Zoro.
Oda made Ray, Katakuri and Oden stand out- if it is indeed WSS Shiryu vs Zoro for final fight you can bet your ass that Oda will make Shiryu, Mihawk and Zoro all look good for it. Much the same way Luffy, Blackbeard and Shanks, and to a lesser extent Usopp, Yasopp and Auger will all still look good. Look at Whitebeard, to this day the strongest person we’ve seen him actually unequivocally beat is John Giant. He’s still held firmly in the top two strongest ever in 99% of fans opinion.
I await my Zoro fan privileges being revoked for this heretical view.