Hard to imagine an arc that isnt focused on Luffy thought.
Also hard to imagine Magellan as a fitting match for Zoro's style but we will see.
No, not an Arc, it's part of Elbaf Arc, it's just that Zoro will be separated from Crew
Actually it's possible entire Crew will be split Post-Wano
Think of it this way
Zoro = Shark + Tiger + Dragon = Demon
In other words, he represents Strongest in Land, Sea & Air (As represented by his Santoryu, Asura & Animal Themes)
When these Three are combined (Such as Asura), he represents Demon & his Goal is to become Demon who Conquers Heaven
So Post-TS, Zoro have faced Shark Representative (Hody) & then Tiger Representative (Fujitora) & then Dragon Representative (Kaido)
And he defeated a Blade User from Sea (Hyouzou), Land (Pica) & Sky (King)
This exact pattern happened Pre-TS & after Three Major Saga, he fought against Kaku
Kaku = Multi Sword User like Hatchan + Troublesome Durability like Mr. 1 + Ranged Attacks like Ohm
And Zoro defeated him by becoming a Trion Figure (Demon/Asura)
So after Zoro defeats King, his next Opponent will be Demon Representative who combines between Challenges of Hyouzou, Pica & King.
And it will be someone who works for WG because after Kaido, Main Saga Villain will be Im-Sama.
Magellan is the one who fulfills all these requirements & complete the pattern, it will be a Fight to determine King of Hell/Underworld.
Zoro's Asura Path + Enma's Name + Tanking Worst Damage ... etc is the Path that Zoro took, cuz he wants to take down Heaven.
And i believe that it will be during this Fight that Zoro Masters Asura. (Unless he does it in Wano first)
And tbh this is just one of the many reasons i believe this Fight will happen, there is actually a Bigger Story that requires Impel Down to be revisited again (Not full Arc, just couple Chapters for certain Reveals)