@Zik:
What are you talking about? When did sky island get completely destroyed?
Whether it's Luffy or a villain is besides the point. I don't see Oda having Fishman island completely destroyed where he either kills all of the inhabitant or forces all of them to move.
Enel destroyed the cloud islands where the Skypeians and Shandians each lived. They were thus all forced to move to Upper Yard.
Oh (almost forgot what you were referring to with the bubbles) yeah. I can see that happening (one of the bubbles being demolished) but I don't think that necessarily equates to the island being completely destroyed.
If this happens there'd have to be some oh we can just live here type of thing for all of the merfolk and fish ppl.
I don't know if I was clear so I'll clarify. I think both bubbles of one island will be destroyed, since there are at least two islands. I think one of the islands will be completely destroyed, like what happened to Skypeia. I don't think he'll show anyone die or anything, but island destruction is fair game.