Has anyone else considered the possibility that maybe the other elven gods are the source of the Blight, or were somehow afflicted by it? It might be that they became corrupted, and that's why they all started doing their mass murdering thing. Andruil was drawn by the Abyss, for instance, and its horrible monsters. Were those demons? Some kind of proto-darkspawn?
We don't know. And with the Forbidden Ones representing things like pestilence and disease... well what if they made the Blight, and it did spread to the other elven gods?
I won't say "OMG the elven gods were really gods for sure," but I do think they were something more than mages--Solas mentions they could be spirits etc. I think there was definitely a time when he did believe himself to be a god. It's entirely possible that they were something more than just spirits or mages, but not quite gods. In any case, they were something that, if they were corrupted, would be terrible.
I doubt if Solas plans to drop the Veil; he wanted to ensure that it became stronger. We would have surely noticed if those elven artifacts dropped the Veil, and I'm pretty sure that Solas acknowledged the harm the Rifts were doing. So why would he then drop the Veil entirely?
No, I think he wants to free the elven gods, but if my theory about their corruption is right...
Bear in mind that the Blight is not only horribly infections, but it's also basically hatred and rage and greed and envy and all that horrible stuff in disease form. So, corrupt such powerful entities and make them filled with hate etc... And yet, there might be a cure for it. It might be that's why Solas is not too keen on the Wardens' solution to the Blight--and it might be that he knows enough about it that his comment that killing the archdemons might make things worse, is true. I suspect it is, in fact, true.
And as for whether or not Solas is lying... well to me, he's lying, but up until he breaks it off with Lavellan "for her own good," I can't blame him. My Lavellan is Keeper's First. I can't imagine her reaction to her boyfriend being Fen'harel would be a good one. Could she move on in time? Sure, she'd probably eventually become okay with it, once she realized that he'd hidden WHAT he was, but not WHO. But, it would take time. Despite all she's learned about Fen'harel's original identity (rebellion), it would take time to get used to the idea that he's not quite what she thought he was her entire life.
I do believe my Lavellan already suspected Solas was an ancient elf. She had no proof, though, and he didn't willingly tell her, so she didn't press. I also like to think she'd understand he had some good reasons for leaving, that she comes to realize he wasn't lying about how he cared for her--he was so sad to leave, after all. But that doesn't mean she'll ever be pleased that he left without any real explanation. She deserved to know so she could decide for herself what to do, not be kept in the dark like a child. Even if he'd never told her until post-Corypheus, he still should have told her.