As David Gaider said, Cole won't be an option cause he's mentally a child. I think Blackwall won't be an option either, because on his profile was stated that he's only interested in being a Grey Warden. Besides that, he's quite old. He's like the Wynn in DAI. I think, Varric won't be an option either, because he might get an own love story with Bianca. And there was stated that he's not into humans. The problem is, due to restriction issues he won't be available to Qunaris either, and I don't think, they'll only create a romance with him for elves and dwarfs (besides that, I don't think he's into elves).
Well, Cassandra, Cullen and Sera are officially confirmed. Scribble (whatever her name is) is as good as confirmed, since it was stated that we'll have "some" advisors as romance options. and due to the fact that Leliana isn't romanceable, only Scribble remains. But I'm not sure, if she's bisexual or straight. On Iron Bull's profile was hinted, that he likes sex with nearly everyone, so I think, he might be available for both genders. If Iron Bull is bisexual and Cullen straight, I don't think, they would make Solas gay, because it would mean, gay gamers won't get a human option at all. That's why I think, Dorian is gay.
so, my conclusion is:
Scribble straight
Cassandra bi
Sera lesbian
Cullen straight
IB bi
Dorian gay
If Cullen is straight, it would make sense to make Scribble straight too. But I'm not sure about that.
...
If we'll get 8 LI's, I think (and hope) it will be a 2/4/2 split.
I think we would get Solas and Vivienne as well.
If Vivienne and Solas are bisexual I think we would get tthe following options:
Scribble straight
Cassandra/Vivienne bi
Sera lesbian
Cullen straight
IB/Solas bi
Dorian gay
If Solas was straight, I think the advisors would be bisexual as well as Vivienne (because I can't imagine her being straight). Than, Cassandra would be the straight option. This results in:
Cassandra straight
Scribble/Vivienne bi
Sera lesbian
Solas straight
IB/Cullen bi
Dorian gay
as for race restrictions, I think IB is not available to dwarfs (and maybe elves). But that's it.
Well, but these are just my guesses.