Well, looks like my suspicions about Solas being the first mage in the party are semi confirmed. Given the fact that Vivienne and Dorian are nowhere to be seen in the party selection screen, it seems logical that you can recruit him before either of them.
I still think we will run into him shortly after the prologue. He will almost certainly be the one to figure out how to use the Inquisitor's marked hand to close the rifts. That screenshot of him holding the Inquisitor's hand up to the rift basically confirms it to me.
Makes the parallel's between Solas and Mordin Solus all the more close, though. An intelligent, hairless non-human the PC runs into early in the game that has specialized knowledge relating to a particular subject. He later figures out how to overcome a severe obstacle in order to progress in the story.
Of course, my aversion to him being a LI is coming down somewhat. At first, I was sort of iffy, but now I see him as sort of a Morpheus-ish figure from the Matrix. I know the characters are probably not much alike, but this image wouldn't leave my head.
Scene: In a secret mansion, Cassandra leads the Inquisitor through a hallway, stopping outside a large wooden door.
Cassandra: A piece of advice: Be honest. He knows more than you can imagine. *Lets the Inquisitor into the room*
*Clash of thunder and lightning as Solas is revealed in the room, complete with mirrored shades*
Solas: At last. Welcome, Inquisitor. As you no doubt have guess, I am Solas. Come, have a seat.
*the three sit down.* I imagine, right now, you're feeling, a bit like Andraste. Tumbling through the Veil?
Inquisitor: You could say that.
Solas: I can see it in your eyes. You have the look of a man/woman who accepts what he/she seens, because he/she is expecting to wake up. Ironically, this is not far from the truth. Do you believe in Fate, Inquisitor?
Inquisitor: *insert one of three responses: 'Yes', 'No' or 'Maybe'*
Solas: Why/Why not?
Inquisitor: *Various responses based on previous response*
Solas: I know exactly what you mean. *starts to twirl a small pouch in his hands* Let me tell you why you're here. You're here because you know something. What you know, you can't explain. But you feel it. You've felt it your whole life. There's something wrong. You don't know what it is, but it's there. Like a demon in your mind...driving you mad. It is this feeling that has brought you to me. Do you know what I'm talking about?
Inquisitor: The Fade.
Solas: Do you want to know...what it is?
Inquisitor: *Nod*
Solas: The Fade is all around us. Even now, in this very room. You can see it when you look out your window, or when you gaze into the sea. You can feel it when you go into battle. Go to the Chantry. When you pay your taxes. It is the world that has been pulled over your eyes, to blind you from the truth.
Inquisitor: What truth?
Solas: That you are a slave, Inquisitor. Like everyone else you were born into bondage, born into a prison you cannot smell or taste or touch. A prison for your mind. *leans back* Unfortunately, no one can be told what the Fade is.....You have to see it for yourself. *takes something from the pouch in his hands and sets the pouch down* This is your last chance. After this, there is no turning back.
*Solas holds out his two hands in fists. He opens one, revealing a vial of blue liquid*
Solas: If you take the blue vial, the story ends, you wake up in your bed, believing whatever you want to believe.
*Solas opens his other hand, revealing a red vial*
Solas: If you take the red vial, you stay in Thedas, and I'll show you how deep the Veil goes.
Inquisitor: *Reaches for the red vial*
Solas: Remember, all I'm offering is the truth, nothing more.
Inquisitor: *grabs the red vial and downs it in one deliberate gulp*
Solas: *Small smile* Follow me.
*the two of them enter a room with an Eluvian Mirror. Dorian is standing next to a rift, his hands swirling magically around it. Like anyone other idiot who sees one, Inquisitor wanders up to the Eluvian and touches the surface*

Solas: Have you ever had a dream you were so sure was real, Inquisitor? What if you were unable to wake from that dream? How would you be able to tell the difference between the dream world....and the Real World?
*the mirror begins to encase the Inquisitor*
Solas: Dorian, do we have a location?
Dorian: Almost have him.
Solas: *Eyes turn ghosty* Vivienne, we should have a location soon.
Inquisitor: *beginning to panic* It's cold....it's co-....
Cassandra: He's becoming Tranquil!
Dorian: Almost there....I've got him!
Solas: Now, Vivienne, now!
Inquisitor: *Leaves the Fade, enters the Real World*