I applaud the amount of effort you have put into your post but there are various contradictions to this theory throughout the game.
To begin with, Solas states that his original plan was for Cory to activate the orb, get blown up and then Solas stroll in and recover it, step into the Fade and tear down the Veil. At this point none of the modern elves had been encouraged to join him. So when the world burned in the raw chaos they would have been destroyed along with the other races.
There are hints throughout that Solas doesn't see modern elves as the same as him. He makes little slip ups, which are far more apparent if you aren't romancing him and thus choosing the heart icons. The most apparent one is after the episode at the Winter Palace when he really is puzzled for a moment when you suggest that placing Briala on the throne will help our people. Then suddenly the penny drops, "Oh you mean the elves." Even before Trespasser my Lavellan was thinking, "Of course I mean the elves, who do you mean?"
The conversation with Abelas is quite clear. He does not see Lavellan as one of his people, but he does acknowledge Solas as such. What Abelas is puzzled about is how Lavellan came by what he can obviously sense is ancient elven magic and in hindsight is probably also puzzled why it hasn't killed him. I have a theory in fact that it is Morrigan's relationship to Mythal and the Inquisitor bearing the anchor (whether an elf or not) that stops the spirits in the Well from blowing their mind. There has to be something inherently dangerous about it and Cole says that basically you will end up with all these voices in your mind. But I digress.
In Trespasser Cole tells us that it was Solas who killed Felassan. This was before he returned to Thedas and Felassan had clearly been awoken early in order to set things up for him and probably do some fact finding. I think that Felassan had been having dealings with that clan for years in order to gather information and use them when convenient. He clearly hadn't tried teaching them anything and was quite willing to let them be torn apart by a demon because it suited his purposes to help Briala and Celene. Yet he had been the one who guided the party to them. Like his master he was quite happy to use people for whom he had no regard and the discard them when he no longer needed them. WoT2 hints heavily that Felassan was another ancient elf, not simply some Dalish who had been influenced by Solas in his dreams. He was also on familiar terms with Imshael. He was able to persuade Imshael to leave his party alone by wiggling his vallaslin, which I think was a hint to Imshael that they were not genuine and reminding him of Fen'Harel and Imshael realised that he was hinting at the latter's imminent return. However, Felassan sees something of Solas in Briala and her desire to help her people, the city elves. He also says to Solas that "They are stronger than you think," about Briala. He also suggested it would do no harm to let her try and help her people. Yet the Dread Wolf disagreed and killed him. According to Cole this was because Felassan had come to see Briala as people. Felassan tried reasoning with him but he knew the moment he allowed his mind to enter the Fade that he was likely doomed. If Fen'Harel saw all elves as people to be restored, why didn't he accept Felassan's argument? Why did he kill him for seeing Briala as people?
To some extent Solas has to keep to his original plan because if he had abandoned it through his interaction with the Inquisitor then he had killed his friend for nothing. Why did he take back the eluvians from Briala when she had been using them to help the elves if he now saw them as his people? Because he wanted them entirely under his control or the control of those that he does consider his People.
Lastly he makes it quite clear to Lavellan that they and all those dear to them will die when he carries out his plan. "I will never forget you" to a romanced Lavellan do not seem the words of someone who expects to see them again some time in the future.
I am of the opinion that the elves were originally spirits who became more material through contact with the waking world, similar to Cole. When he brought down the Veil and severed their connection to the Fade, those that were born after became gradually more and more disconnected from the Fade and thus more and more material. They still have some magic in their blood and so it may well be that as their material bodies are destroyed, their essence will return to the Fade as a wisp that will regenerate over time and it is in this sense alone that you can regard him as saving the modern elves. Like his friend that we saved but was then too damaged to stay in their original state, when the elven wisp recovers they will likely not remember anything of who they were before, although it is possible that for a romanced Lavellan if the strength of Solas' memory of them is sufficient, something of their identity might remain. For others though, it will be as though they are a new individual, which will probably be for the better as they wouldn't want to remember anything of what they were before or who they had lost.
For the ancient ones it may be different because he can instruct them to enter uthenera until it is over and because they are still in their original form from just after the Veil went up, they will simply be reconnected without losing themselves.