What prediction would you make for the loyalty of the Ironborn to their king Euron? Will they follow him blindly or if it gets as sinister&destructive as the preview chapter implies, will they realize he is a monster who might lead them to their doom and turn on him? Or will it be too late for them?

Well keep in mind, the Ironborn are not all in one place: there’s some left behind on the islands, there’s some on the Shield Islands, and there’s some with Victarion. 

So I think some will survive his intended sacrifice, but I think it will be less a matter of turning on him as the survivors grappling with a disaster that makes Lodos look positively bloodless by comparison.