My theory is that while things may skew unevenly for certain race/gender combos, everyone will still have at least two options, with human characters having All The Options since humans are the most common. This means that there probably will not be two characters of the same gender who are race-gated, since it would probably result in one group getting only one option. It also means that the remaining LIs are all bisexual.
My theory may be completely wrong. It's just a theory.
Right, I'm pretty sure Vivienne is going to be an option so that there will be an even number of LIs for all genders/orientations. Most likely she'll be bisexual, and she'll probably be race-gated due to her love of power (Cassandra being the first character to appear, she's unlikely to be race-gated).
As for the guys, I am thinking Iron Bull and a toss-up between the three others.
Varric - In his favor, he's probably the first male character we pick up. Usually the first two are romances. Against him, Iron Bull will almost certainly be race-gated, and Varric has expressed that he is not into humans. He might even go so far as to be dwarf-only. He's also probably straight, which would reduce options for gay/bisexual male characters. Also against his favor, Cullen is already a confirmed romance returning from previous games. Would they do two returning characters as romance, particularly when both are male? Still, he's an option and there are likely people on the dev team who wanted it.
Blackwall - I don't really know much about him. He seems to be mid- to late-40s, to me, but beards make men look older. This is not too old for romance, contrary to some opinions, but what may work against him is that he reminds a whole lot of people of their fathers. Still, that wouldn't stop the devs. He's got a noble personality. He might be too interested in doing good, and self-sacrifice, to do a romance. Otherwise, really I have nothing for him and nothing against him. No evidence either way besides the devs' "soon," which just as likely meant that players would know one way or another "soon," rather than that he will be a romance "soon."
Solas - The only male elf. Elves have traditionally been romances in Dragon Age games, which may work against him rather than for him if they want to break the mold. His VA was just announced, though this could easily have been to smooth things over for when he is NOT announced as a romance. He is said to be "open-minded," which could lead into his being a bisexual romance, but with his focus on the Fade, he may be asexual or too busy to be a romance. In his favor, his VA is apparently well known for playing a bisexual character on the show Torchwood. This may or may not have had something to do with David Gaider's preference for that voice actor to play him. And yet on the other hand, would Patrick Weekes have written two romances, assuming Iron Bull is one?
So yeah. For me it's a tossup between the last three males, with Vivienne being all but a certainty.