Exactly like that, honestly. Lavellan would have to initiate but he would totally do the wrapping around her thing.
I feel like he still has to change somehow. If that's moving forward or if he ends up falling back, he needs to go somewhere. I like to think it will be moving forward even if that's the hardest way to go. I would be happy with a promise of someday for Lavellan and Solas. If they can't be together right then and what he's doing isn't a big mistake, at least there would be something to go on other than the break up and him breaking everyone's heart.

What did you do with scintilla why are you so optimistic now?!
If they can't be together, I would really like a big affirmation of his love for her. Not the self-sacrificing "you're free" nonsense we got, but a real, honest-to-goodness confession. Like Tidus and Yuna in FFX. That I would be OK with. That would satisfy my need for happy feels. Then let whatever tragedy that needs to happen happy.
The thing for me is, I don't want him to be wrong. Not completely. That's a story that's been told more than once, and even if the outcome of whatever is going on is oh-****-worthy, I still want it to be more complex than Now I Am A Villain. Or even I Must Do This Thing that makes him an anti-hero. Something that really is shades of gray, morally complex, and really makes you think. Not just standard bad-guy fare. Not a typical oh, la, he MUST follow this through because he's tragically silly and feels he must, but because one way or another, he really needs to in order to prevent something worse or help out in ways that might not seem like it at first, but really is what is necessary.
It might sound like this comes from a place of bias since I romanced him, but it honestly is just wanting to see the character and his actions be more involving than that. If all we ever get is a Fade dream of goodbyes, fine, but I'd rather that and he be something more than going down the ho-hum path in which he'll just be a boss fight in a DLC.
I got faith, but I still worry. 
Oh, I 100% agree with you. Like I said I think if he's straight-up wrong and on the railroad tracks to wrongness it would be really static and boring for players (and Weekes). I think we'll get something.
I could actually see a situation where you can convince him to abandon his plans entirely, and then new-god Morrigan comes in and completes them for him. As much as they fight they seem to have similar motivations, she just knows a lot less. Spread the morally ambiguous romances around!
I think it's just....what bioware writer wants to admit to fans they wrote a romance to be sad...lol...
I wouldn't assume it means anything more one way or the other. I agree with his choice though, the game ending is overall very happy, the story needed that little bit sorrow/loss at the end, that the Solas romance gives. That's why it's my favorite.
I hope he means he wanted it to be sad here, and not sad forever. I'm totally in love with it being sad in the main game. I'm so involved in part because it's so heartbreaking. I still think all players - regardless of romance - should have a chance to side with or against him, or affect his character in some way.