Hello everyone! I hope you are having a great weekend. It's so wonderful to come in from a day out and see all the discussion.
I've read through all the comments. Just wanted to make some contribute with some of my weird observations 
I'm in for Abelas as a LI for DA4 too! and thanks all for not spoiling this last DLC! (my hand is itching to google what has been datamined, but I will be strong! I want it to hit me as it comes when I play it!)
Since you are talking/theorizing about the nature of Elvhens, I leave these thoughts here that i'm trying to connect but failing to do so 
1) After Tom, when you speak to Solas, he says that the 'creators' as Dalish call them were not gods, but powerful mages or spirits or something we have never seen before (I'm betting on the latter one)
2) During Cole's mission, Solas says one cannot change his nature by simply wishing it, and immediately averts his look from Varric, looking at quizzy (or maybe not looking at her, but recalling/remembering something that contradicts what just said?)
3) If you make Cole more human he says in a banter that he never expected to see it (spirit made human), and Cole says "when did you see it again?" which he of course denies, saying that Cole misheard his thoughts (maybe they are powerful spirits that changed their nature?
or maybe that how they lost their immortality?)
4) If you meet Kieran as an elf, he says "your blood is very old [..] why do you want to look like this?" (ehmm meaning I could look like something else if i wanted?)
5) During ToM, when Abelas says to Solas "Elvhen such as you?" I get the feeling that he knows who Solas really is, there is a slight bitterness in his voice when he says so (or that how it sounded to me
).
6) Again during ToM, when you first meet the sentinels and talk to them, Solas watches the conversation by looking at quizzy and Abelas when they are talking. But when quizzy asks him to say something to convince them, he answers some sorts of "why would they listen to me?" and for the rest of the convo he looks at the floor, remembering (?) and being sad.
7) There is a banter between Solas and Cole, where Cole says "you are real, everyone could be real, this changes everything, and nothing" (something like that). Everyone seems to think Cole referes to quizzy, but what if that "you are real" refers to Cole himself? He is a spirit made "real" material being.
8) During the break up scene, Solas says to quizzy that she has "a marvelous and bright spirit" and "in another world, not this one". sounds very much what a spirit (or something we have never seen till now) would say?
If someone has an insight, I'll gladly listen!
Hang in there! Not long now! It will be all the more sweeter when you experience firsthand and not from spoilers. All wonderful points. I enjoyed reading them 
I've always believed that the Elvhen pantheon was part of the lore where they refer to the Maker's first children. The Dragon Age universe borrows from Tolkien in areas. Tolkien's elves were known as the first children and humans the second children. Before Tolkien's elves were awoken, the seven gods helped bring the world into being. I think the Elvhen pantheon is the first children that we see in DA lore. Those spirits that the Maker created but then decided he wanted something different and lcreated elves and humans. I keep wondering if we will find out that this Elvhen pantheon was comprised of the spirits charged with teaching the elves or if they fell in love with the Maker's new creation and decided to teach them. I think the Elvhen pantheon started off as guides to the elves and then I think once Andruil entered the Void they became corrupt over time. My current theory is that the Void was created as a mockery of the world by spirits jealous of those who were named Creators by the elves. The Forgotten Ones wanted to control the Elvhen instead of teaching them. The Void became their domain and represents the fall from paradise and loss of innocence. It's my weird guess.
But when quizzy asks him to say something to convince them, he answers some sorts of "why would they listen to me?" and for the rest of the convo he looks at the floor, remembering (?) and being sad.
I noticed that look! There was guilt going on there. Now why Solas was guilty I'm uncertain. Maybe he hated Inky seeing the life of the sentinels. It has to be painful to see people he tried to help to freedom still bound in servitude. Maybe Solas had his own sentinels just like Mythal and he is ashamed of being reminded. But I do agree there was something odd with that exchange.
Oh I think Abelas is annoyed with Solas if for no other reason than the fact he caused a big mess all over Elvhendom. But Abelas is really a product of slavery and at that point in time he is simply not able to see past his duty to the bigger questions. I still haven't forgiven Flemythal for leaving those sentinels in that temple.
I wonder if Solas can see her spirit, like her actual aura or something. I agree with what another person said that for Solas it isn't about physical looks. He loves Lavellan for who she is not her side benefits (that's why he calls them side benefits)
This is all awesome stuff that I love to talk about.
Here are some of my thoughts on a couple of the things about some of these things.
1. I think the Pantheon was a mixture of all three. What I'm really curious to see is what are "things we have never seen. " Would be awesome if they explain that in this upcoming DLC>
4, I think Kieran is actually referring to the vallaslin here. We all know romanced Lavellans find out from Solas that the vallaslin were slave markings. Could be wrong, but it's just what I think.
5. I actually think thisis the moment that Abelas realizes Solas is an ancient elf like him. I know I am the minority on this, but I don't think ABelas recognizes Solas at all until that exact exchange. The main reason I feel this way is just based on the Abelas' demeanor following that exchange. He relaxes a lot after Solas' reply of "Yes, elvhen such as I." Once again, could be wrong. Only time will tell on this one.
Everything else I'm just sitting around waiting for more light on the subject.
Soon. Tuesday.
Answers......hopefully.
I'll die if none of this answered. If we have to wait another two years for more info I'm going to go camp in front of BW's headquarters begging for the answers instead of change.
Yes I'm eager for answers too, although I dont want everything explained
I like this mystery, and the puzzle pieces we are trying to connect, if there is to be a DA4, there should be some mystery left for that 
About 4) I dont think its about the vallaslin, because he says to a qunari quizzy "your blood doeas not belong to your people" so Im guessing he is referring to the origins of the race probably (qunari having dragonblood maybe, if what Iron Bull says stands true)
Agreed! I don't think they will answer everything. But I just want enough to understand that exchange in the temple with Abelas. I wonder if Kieran is referring to how spirits look in the Fade as opposed to their grotesque form outside of it. I wonder if once in the Fade an elf can imagine themselves differently.
I love the thought of Solas being a former slave raised to Semi-God, and thats how he knows how to remove Vallaslin, this could be why Abelas did not abase himself when he recognised Fen'Harel.
I don't think Abelas is too happy with Solas. If he was going to blame someone for the current state of the world it would be the Dread Wolf. Yes, he says the Elvhen warred on each other but the root of that was probably having the gods locked away. Perhaps Abelas wasn't swayed by Solas's rebellious solution to the problem of the gods. I'm not sure. But the weird thing about Solas is that he had that ability to walk between the pantheon and the Forgotten Ones and I want to know why. Was he a bit of both or something that was constructed by Mythal? I really want more information about his relationship with Mythal too.
1 & 3) I'm with MayriyaNoori here, I also think they were a mixture of the three. Maybe they were like Cole in a sense, that they are spirits or some other beings in the Fade made material. That same connection with the Fade would be why magic was "part of being elf", as Solas says.
4) Before reading Mayriya comment, I thought this referred to the fact that elves were able to shapeshift at some time. But now I think it makes a lot of sense that Kieran is referring to the vallaslin.
5) I interpreted it as "Elvhen such as you, even if your mortal companions here now nothing of it?" But that may be just me being bitter for not having the option to say "HAH! I knew all that 'I saw it on the Fade' was bullshit" 
Mayriya, I'm curious on this one, why do you think that's the moment Abelas recognized Solas? You think Solas hid it until then or it just took Abelas some time?
6) I'd say that's Solas old guilt; elves listening to him or even being led by him seemed to have disastrous consequences, so he doesn't think that none that remembers what happened (and Abelas must know for sure) would listen to what he has to say. Either that or it's to keep his hobo elf act: I'm just a poor elf that spends his days wandering the Fade, why would an ancient sentinel listen to me? I'm more inclined on the latter.
7) This has been discussed over on the Solas thread, and I quite agree with what people said: modern people of Thedas are less real to Solas than ancient elves. As he repeats again and again, not even modern elves are his people. But if they are real, if they are viewed as individual people worthy of love from ancient beings as Lavellan is, and they are eventually harmed by whatever Solas is planning; then it changes everything, because his guilt is greater, and nothing, because Solas has made it very clear that nothing will stop him from doing what he feels is his unescapable duty.
8) In connection to 1, if ancient elves were part Fade beings and able to shapeshift (at least we know the creators shapeshifted into dragons), looks must be not important to Solas. He definitely thinks Lavellan is beautiful, but what matters is that she has a unique spirit.
I have something of my own to add; by reading all the lore discussed here and the Solas thread, I am almost conviced that the elves of the Dales were the slaves that Solas (or the events put in motion by him, or the creators infighting, I'm not sure about this one) led to rebellion. And that the Dalish are descendants of those elves, that's why they are still wearing vallaslin. Do you agree on this? And what role do you think the sentinels on temples like Mythal's and Dirthamen's played? I don't see Abelas just sitting on his hands while his world is falling apart; but I don't see him and the sentinels just leaving the temple empty.
I wonder if Abelas figured it out once Solas cast magic. Have this strange feeling that Elvhen magic is very different from regular magic. Solas is going to know how to accurately draw from the Fade and his methods are unique compared to the modern mage. I'm thinking of that conversation he has with Dorian and Dorian attributes the method to Tevinter, when in fact, it is elven or rather Elvhen. According to Dragon Age Heroes game, Abelas is a mage. He's going to feel that difference and recognize Elvhen magic immediately, in my opinion.
Abelas says he shut the doors to the sanctuary, so I took that to mean that when Elvhenan really began to fall he locked the sentinels away for good and slept.
I agree with this, and I think that those slaves were the ones who killed Mythal and other nobles, like Felassan tells us in "The Masked Empire". And if this uprising was Fen'Harel's fault, well, that's an awful lot of guilt to be carrying around, for sure.
There was someone on reddit who came up with this theory about Mythal's murderer. He was talking about how there are these pictures that depict Mythal taking vengeance on Dirthamen and I think basically killing him because he was killing elves in droves. I need to go find the link. But basically, it was suggested that there was a divide in the pantheon and lines were drawn. So I'm wondering if there was an all out war between the Elvhen or if they plotted and killed Mythal and then Solas locked them away so that they were not able to keep killing each other.