I so enjoy all the crazy in this thread, even though I'm usually just lurking.
I am feeling a bit more positive about Solas' chances for being a LI now, I really like Carpools ideas on tumbler post.
I know that its been discussed that how many romances each writer wrote is not very relevant, but I do kind of think it would be a bit surprising if the final two were written by the same person... If I'm right about that then we're only getting either Varric or Vivienne, and in that scenario my money would be on Vivienne.
So, in this scenario it is between Blackwall and Solas, and although it would appear that Solas is generally more popular than Blackwall, that can't be taken to support that he is a romance, but Solas would seem to provide a better contrast from the others than Blackwall would, and I don't think that is something that would have escaped their notice.
One thing does seem clear - Solas is important, I think carpool is right on the money pointing out that images don't appear on front covers without thought. I think it is very likely that the outlooks of both Solas and Vivienne will represent two different approaches that can be followed in the game. If this is the case I will be very glad to have a male elven character who is more essential. I love Zevran and Fenris, but do with they had been more integral to the main plot.
....buuuuuttttt, this is all just speculation built on very little substance 