I did not think that Oda would go that far as Imu's 3rd form really is gigantic, but I always thought that he would go that route earlier or later.
Ice age ocean freeze, Banaro Island, quake tsunamis, Fuji's rubble lift, King Kong Gun, PH terraforming, those logia avatar forms, Kaido's island lift & flame dragon torch...
I think a lot of the final saga battles will need island wide areas in order to take place, cause of the sheer destruction scale and Imu takes this to an entirely different lvl.