I wanna add something regarding Upcoming Events.
Following Saga Structure, we could say that last Major Story Parts were MF Saga, Fishmen Island, Dressrosa, WCI and then Wano
I noticed that during MF Saga, Oda teased Doflamingo and Smiles, Two Saga later he was Main Villain and Destroying Smile Factory was Main Objective
During Fishmen Island Arc, Oda teased Big Mom and Tea Party, Two Saga Later she was Main Villain and Ruining her Tea Party was Main Objective
During Dressrosa Arc, Oda teased Kaido and his declaration to start World War, Two Saga later he was Main Villain and stopping New Onigashima Project was the Main Objective
This means that Villain of Next Arc/Saga was teased right before Wano started alongside his Evil Plan, and that's obviously Imu and SHs need to stop his/her Goal to "Remove certain Light"
And as Build Up for each Fight against those NW Villains, Oda makes one of Important Characters need Luffy's Help in stopping that Villain (Law for Doffy, Sanji for Big Mom, Momo for Kaido)
As for Imu, it's building up to be Sabo, suggesting that Luffy is indeed gonna meet Sabo on Next Island and they will hear from him about Imu
But Imu is in Mary Geoise and he rules other Major Islands such as Marine HQ, Impel Down, Vegapunk Lab ... etc so be prepared to see SHs splitting up