I saw Blackwall being a romanceable characters about a month or two ago, and at that time, I think many people found that concept hard to believe. What I did not see/predict, however, is Vivienne NOT being a romanceable character, and instead, the final romance slots going to Solas AND Blackwall. Wow... Just wow...
I'm happy for all the Blackwall folks, though, because, in my very personal opinion, Blackwall needed some sort of boost to his popularity, because he was just...there. He just seemed so forgettable compared to the other 2 companion warriors in the game (Cassandra and Iron Bull), as well as the war(rior) advisor (Cullen).