Oh, I would be completely unsurprised to see the Forgotten Ones take a major role. They've been nibbling at the edges of elven mythology since Origins, with Jaws of Hakkon actually letting us find the first physical traces of one of them (Geldauran). I'd be curious to see the Fen'Harel memories mentioned as sidequests and if they mention them in any capacity.
The problem, of course, that all of these interesting lore reveals are buried under absolute shit-tier writing, so it's become very hard to care.