Zoro doesn't have to beat Shanks, nor will he beat Shanks. You are taking certain things (not even in the manga), and stretching them beyond their breaking point to fit your internal Zoro love.
Let's forget my Zoro love for a second. Shanks is a powerful swordsman. Why wouldn't Zoro take a shot at him? What stops him from defeating him?
Shanks doesn't have the title of WSS. He is however a stronger pirate, one feared by everyone. You make the mistake thinking that everyone with a sword is a swordsmen exclusively, or someone who has dedicated their life to the sword the way Zoro and Mihawk do.
A stronger pirate? All that being a pirate includes, such as crew, allies, etc? Sure. As an individual? Not. He isnt feared by anyone, you just got fooled by Oda...
Whitebeard and all that he brought into Marineford with him was deserving fear a lot more than 10 members of RHP and still, nobody cared. If you think Shanks and his several crew members are more fearful than entire might of WB pirates and his allies, I cant help you...
No, I dont think that. I think that other abilities didnt stop any swordsman from being a swordsman and Oda didnt exclude any ability in a fight.
(and also note that there is no indication that Mihawk was even stronger when the two dueled, all indications are that as swordsmen, they were equals, and haven't fought since Shanks lost his arm. This is all canon. It's not in a vivre card, it's not in a book that no ones read. It's in the actual manga!)
I'll tell you also what's canon from the actual manga: One-armed
has-been.
I think you have to understand something. I'll try to help. THE MANGA ISN'T ZORO'S STORY. Shanks doesn't exist for Zoro to surpass. He exists for Luffy to surpass. And surpass here doesn't mean "beat", since Luffy worships him. Unless something hidden in his life comes up, Shanks will not be an enemy, a stepping stone. He'll be like Whitebeard to Luffy's Roger, someone who shares a drink with him as Luffy goes off on his journey to One Piece.
Yeah, it isnt Zoro's story despite being also his story since chapter 2... Luffy fans seem to have a problem sharing the cake. "Mine, mine, mine..."
Sure, he doesnt exist for Zoro but there are other ways of surpassing Shanks for Zoro, by defeating a man above him.
Mihawk's character's point for Zoro was established early in the manga. Shanks has never played a part in that. He only plays a part to you because you are obsessed with the notion that Zoro, the non-lead character, the man Oda sidelines for months, or years as he focuses on the actual protagonist, will be the strongest. This is entirely your invention. It has nothing to do with the actual manga, how it's been written, what has been set up.
It's manga fact that in Whiskey Peak they were equal despite plot babysitting Luffy and it's also fact that Zoro kept getting upgrades after WP while Luffy got nothing. It is manga fact that one was busy fighting animals for 2 years during TS while the other didnt have nobody else to fight aside from Mihawk.
Oda sidelined Zoro for years to focus on actual protagonist so he can give him Zoro's role in Wano of being a muscle while Zoro is the one being involved with the actual plot more than anyone else, a role which usually belongs to Luffy.
The whole point of Mihawk's character is to stand above all other swordsmen, especially above one-armed has-been.
By EOS, Luffy will be the "strongest" character. Zoro and Sanji will be close behind him. They'll never fight to see who is strongest, so we'll only have the manga to base this off of. The manga where Luffy will continue to fight the strongest enemy while Sanji and Zoro fight their 2nd and 3rd in command. And that's fine. For normal people, it really is.
I hope they do end up fighting to see who the stronger one is among fighter and swordsman, as they wanted to see in Whiskey Peak. For me, it was completely fine that Luffy needed Zoro's help and help of others for actually toughest opponents pre-TS and completely fine that he didnt do nothing more than others except having the last hit. It is also ok, that he needed help of others for every opponent that came after Don Chinjao. Is it ok for you?