@MetaMario I wonder how Kuma's flashback will be structured.
Usually flashbacks are based on a single event, and the entire story builds up to it. Anything important but not directly related to that event is glossed over quickly.
For instance, Law's flashback is about Corazon's death. As such, it's structured around Law meeting and befriending Rosinante, so that the death properly kicks us in the guts. There are other important stuff for Law, like his origin in Flevance and that place's history, but that is not experienced in detail because it's important to know but not that important for the flashback's main purpose.
But so far we don't know anything about what event is the "center" of Kuma's backstory. Is it his life as a slave? He as king of Sorbet? He meeting Dragon and forming the Revolutionaries? His story with Bonney?
Kuma's life seems to be full of important events but not a single one that could be the focus of a flashback, at least for now. A flashback that just goes from period to period, chronicling someone's history, may be very interesting but lacks narrative momentum (the buildup to tragedy) and a climactic conclusion (the big tragic conclusion).
In the case of a series of events in his life, I think the better narrative option would be a series of smaller flashbacks, each coming at an appropriate time in which they are meaningful to the current events. Like, something in the present brings the subject of God Valley or slavery, so the story shows a period of Kuma's life related to that. Then another moment in the present calls for info on the Revolutionaries, so we get Kuma's memories related to them. And so on and on, until we get all the pieces and reach the end of his journey.
So, I keep wondering which option Oda will go with. But whatever the case, I feel we will get a in-depth look into Kuma's story.