That is something I love from One Piece.
In other animes, you know there is 1 final boss and who it is. Or someone behind who we thought the final boss, its just 2 sides.
But in one piece, everyone has their own strory, their own faction and you dont know who is gonna be the final boss. Heck, Imu is already fighting while Dragon power is still unknown lol.
If Imu aint the final boss? Is it Teach? Or Maybe Enel?
What about Shanks?
The Navy?
Or even fucking Doflamingo? Lol