Definitely possible! I think if this is his goal, then the danger is that there's a high likelihood of everything going wrong:
a. He sneaks into wherever he's trapped all these people, and awakens one of the trapped elven gods
b. The people trapped in limbo have long gone crazy from being held in a fate worse than death
c. The people are long consumed by the elven gods but their 'presence' is being mimicked like bait.
Actually, I'd say regardless of what Solas is planning to do, there's a huge likelihood of everything going wrong.
Hmm. This is all still half-baked theory in my head, but don't think anyone in the city of Arlathan survived the fall. There may be scattered examples of surviving elves, sustained by Uthenera in remote tombs reachable by eluvian, but I imagine their numbers are small at this point. The only examples I would count on being preserved, at least for now, are those who would have been airborne (in dragon form) during the attack, directly before the City was sealed. ie: the remaining Old Gods.
"...wait. What attack?"
Yeah. It's shaky as hell and so far out there it's not even visible from left field, but hear me out. Like all nutjob theories, it sorts out some important threads at the cost of tangling others: in this case, the nature of Andruil's weapon and how the Golden City turned Black.
The translated elven codex that describes the weapon came up bit a while back (many, many pages ago) but I'd like to tweak my concept of what it was, exactly. "Shaking the radiance of the stars" into "grains of light" would be a much more apt description of an extremely powerful laser, conceptually. A laser whose source (stars) we then trace and decrypt back through Dalish myth to be radioactive energy from the (potentially blighted) lyrium “Blood of the Sun”.
So... laser. Very, very powerful laser. Now consider the effect of a femtosecond laser pulse on a metal surface.
It turns it black. Pitch black. Permanently- not like a layer of carbon soot that can be rubbed off. The intense heat restructures the metal on a microscopic scale such that it becomes an incredibly effective absorptive (instead of reflective) surface. This holds true for any metal, even though on an atomic level it is still entirely made of up whatever it was before- silver, or aluminum, or… gold.
How much of the “Golden” City’s description was literal and how much was just rhetorical glorification is debatable, but as the greatest city of the Elvhen Empire, even if it were not literally entirely golden, it was probably liberally accented with the gaudy display of wealth and power that gold conveys. And if a weapon like this was turned on the city? Every golden surface would be indelibly blackened.
An interesting coincidence, but probably not worth more than a raised eyebrow on its own. What gives it a bit more credibility, to me, is the peculiar defense system we run into in the Citadelle du Corbeau in the Exalted Plains: the one the humans clearly neither understand nor control. A lesser weapon, certainly, but seems to confirm that beam weapons were part of the ancient elven arsenal, and gives a vague hint at how Andruil’s version might have worked.
Anyway, the threat of this weapon being turned against Arlathan may have been the last straw and trigger for Solas to shut the whole thing down, possibly in a bubble of localized space-time moments before the weapon's release. (Much like the "fade magic? what the heck is that?" song and dance he gives you at the beginning of the game, I'm not sure I believe him when he claims ignorance that magic could be used to decelerate/accelerate time. The fade is all about warped-physics-as-magic, and that's kind of his Thing.) If he did make the attempt, he may have been able to slow relative time to a near crawl, but he couldn't have stopped it entirely. As decade after decade passed in the outside world, Andruil's arrow of light would have eventually found its mark, and by the time the Corypheus got there, the inevitable had happened. The City was black and utterly empty- its physical inhabitants vaporized, residual lyrium blighted by the energy source of the apocalyptic weapon that had been unleashed there.
Bit dramatic, yeah?
I don't know that I actually buy any of it. ^w^ But until I can think up an alternative that fits, this is all I've got.