Here's my thoughts on the remaining LIs, in order of how likely I think they are to get a slot;
Iron Bull
There have been enough hints over Twitter for me to think this is happening. I'll be surprised if he doesn't get a slot. It's mostly just that. I also think he makes a lot of sense as a gated LI, though, and we need a gated male. Neither Solas or Blackwall makes much sense as a gated LI, from what we know, and I think they're more likely than Varric for the other slot.
Vivienne
I think the gender and sexuality counts will be equal with some races getting less options, so I think she's in by default. I also think she makes the most sense out of the women to be race gated, which we'll likely have. I think it's a bit silly that people say she's "too ambitious" to be an LI. People realizing that work isn't everything is a pretty standard romance plot. That's not even to touch on the fact that the vast majority of our companions are "ambitious". Otherwise, they probably wouldn't be in this line of work. Dorian is trying to change an entire country, Cassandra started the Inquisition. These aren't ambitious people?
Solas
It's close with him and Blackwall, but I'm leaning towards Solas. He better balances against the other options. Iron Bull, Cullen and Blackwall are all warrior types. Not just in class, but in personality. They approach things from a specific perspective. Solas is a decent contrast, both physically and in personality. So, I'm going to guess it's him.
Blackwall
I wont be totally shocked if it's him, but I think he may be more of a mentor type. That's how his archetype is usually set up. They also might not consider someone close to their calling as a good option, since Thane's illness in ME was not well received. I could see him as being like Wynne with a better sense of humor.
Varric
I think there are several reasons he doesn't fit. He's not well conceived as a bisexual LI and I believe the remaining will be bisexual. His characterization would have to change a lot for him to not come out extremely slanted towards women, which isn't totally fair to guys. He's said before that he didn't like humans and I think it's less likely both gated options will be males. I'm also doubtful they'll gate against the most popular race (humans) in favor of the least popular race (dwarves). Then there's the obvious Bianca situation, which I think we could be solving this game. It seems very possible that he will be reuniting with Bianca.