I think it's entirely possible that the modern elves are so far removed from their ancestry that they could never again become what they once were. They may actually be fundamentally different from the ancient elves in ways that aren't necessarily obvious. There must be a reason why Solas acts as though it's hopeless, after all. Perhaps they are sort of like the Tranquil; somehow forever severed from that which made their ancestors "truly" elven.
I agree with the context of what he was trying to do with the veil part but im not so sure about the other part. Being a Elf for the elf blooded people of thedas shouldn't be simply classified as some kind of genetic trait that can only be traced to Solas and Abelas type elves. Even modern Elves were said to have hard to place ages based on appearance, and depending on whos version of the them you go with lived longer lives than other races though i am aware that they have recently released information that suggest that all races live about the same life span, but the ancient elves were known to be immortal more so because they slept after a time for whatever reason, this could have been a part of their life extending process, perhaps even a rejuvenating process.
Solas continued interest in the Elven artifacts throughout the game, turning them on, saying they strengthen the veil to me seems more like a lie now and is in fact going to be used as a resource to remove the veil entirely. Corypheus way of opening the veil and causing the breach was the incorrect way to do it most likely, a human approach if you will in and of the fact that it was a bumbling attempt that caused more disruption and chaos than Solas originally wanted.
Hmm now im thinking about all the times Solas had such polarizing views that were generally assumed factual.
1.) Solas questions Blackwall about the Grey Wardens and their continued efforts to stop the Blights by defeating Each Archdemon that arises. At the end he says I hope it is true, but you get the feeling he isn't being completely honest and is holding back some information. What if The Blights began as a tool used not by the Maker to punish humanity, but by the Elves of ancient times as a purge tool to try and cleanse the world of humanity and other humanoids influenced by their actions. What if they had another means to end the blight after it had served its purpose and then return from the Fade to a now cleansed Thedas... this sounds a lot more in line with what may have been when you consider Solas's actions.
2.) After the well of Sorrows Solas claims to have begged female Lavellan not to drink of the well, and when he explains his disapproval it comes off more like a parent scolding a child for making a bad decision. When you tell him that he doesn't even believe in the old gods, he becomes flustered as if he almost let the secret out. Solas always knew that the old gods were more like Ancient Elves who had a greater understanding of magic that the current citizens of thedas could never imagine. In fact im starting to think the difference and significance between him revealing that the Dalish honor their slave heritage is much more telling now.