The only way I could see Zoro vs. Mihawk still unfolding is if Shanks is turned into an antagonist. Which would be really out there at this point, but not impossible. At least I can picture a scenario where Shanks tries to stop Luffy from stirring up the hornets' nest that is the World Government.
Not because he's in cahoots with the Celestial Dragons, but because he understands that the consequences would be too severe. Oda left a few breadcrumbs along the way if he wants to go that route (Roger and Garp stopping Rocks, Shanks casually meeting the Gorosei, Rayleigh's somewhat defeatist attitude during Saobody, Luffy himself anticipating a confrontation with Shanks….).
This would obviously not turn Shanks into the final villain, but it could be an alternative to the Redhair Pirates dying - and it does open up the possiblity of a Zoro vs. Mihawk encounter before we head into the real endgame. Picture a clash similiar to what we have seen with the Roger/Whitebeard Pirates, just a lot more significant. Not your typical fight to the death, but no friendly sparring match either. Some fanservice, some heartwarming moments (mini party after, Usopp hanging out with his dad etc.), some tough talk.
If this scenario can be executed in a satisfying manner is a different story, but it's the only option on the table that isn't mega weird. Although pacifista'd Mihawk would be hilarious….
Could you elaborate on how you feel Imu has been foreshadowed and built up? Because to me the main issue i have with him is that he came from nowhere with no build up. Just curious about your read
This wasn't directed at me, but I would like to ask people a related question: Did you really believe that the World Government (running for 800+ years) simply relied on 3-4 people of Admiral-level strength to keep the status quo all this time? That they were just always lucky to have the demigods of their time on their side? Generation after generation? And that those demigods would never even think about just going rogue on the entire system and take over (Kuzan times four)?
The moment Oda established the Balance of Power concept I expected that there simply had to be a greater force waiting behind the curtain. A "nuclear option" everyone wants to avoid, but still the ultimate insurance that protects the WG from falling. Even if the strongest individuals in the world team up against it.
So to answer the question in the quote: No, Imu itself wasn't forshadowed, but I actually took for granted that something like Imu exists. Not necessarily a person, but a red button ready to be pressed if the World Government is threatened at a substantial level. It could have been a literal nuclear bomb made by Vegapunk, or the battleship Pluton, or Gorosei Docking, but… something.
At this point this is what I see in Imu, at least. She's Uranus, the ancient weapon in possession of the Government, the nuclear option. The reason why Pluton was built, the reason why Roger was interested in Poseidon.
If Imu is basically a Kaguya who has to be fought directly is the question, but I don't see it. She's like Shirahoshi, just with a different personality (which could be anything, from scheming mastermind to spoiled brat to religious nutter).
It would explain the Gorosei tiptoing around her, while she's not involved in the leadership of the WG for the most part. She's sitting in her golden cage, doing weird shit, and if push comes to shove she can be "unleashed" to purge whatever.