Yeah, Nidhogg being vengeance incarnate worked for the story. My minor quibble is with Thordan being pretty lame and Lahabrea being completely wasted. What happened with Lahabrea is even more of a bummer after Shadowbringers.
Well we'll just have to see what ever the fuck is up with Pandemonium in Endwalker.
The raid being about him is even more intruiging since they've already said that 6.0 will be the conclusion of the Hydelan and Zodiark story, meaning that everything for his raid series may potentially be part of the setup for the next story arc.