Seems there are still some supporting gender plus race restrictions on romance options. I am going to give my opinion on this and if someone wants to try and prove me wrong go ahead but it won't work until its officially announced. Lets see the reasons we have been given for race restrictions has been animation and story reasons, with the recent announcement of IB as a love interest and as a un-restricted one to me that means the animation issue may no longer be a reason unless it has been said otherwise, so we can assume story reasons are why, so I will TRY and give my reasons why I think they could be restricted and then why they won't be.
Why
Cassandra- She is one of the only ones we know a lot about thanks to her not really being new to the series, with her being male only and given what I have seen of her in the past I could see Cassandra not being into Qunari and maybe even Dwarves, I really think out of all the races Qunari might be the one restricted the most even if they aren't part of the Qun for story reasons BUT then again Qunari will be one of the most played races in this game so that might factor in to.
Cullen- Given Cullen's track record and seeing how he isn't the most layed back person in the series, I could see him only being interested in female humans or elves, given his religious beliefs and since he was in Kirkwall during the Qunari attack I could see him not attracted or interested in Dwarves or Qunari.
Dorian- I have not looked up a lot about Dorian to tell you the truth, I guess he could not find some races attractive but with him being a outsider and already seen as a heathen by most he could careless about what race he is with.
Sera- The biggest reason people have given that could make Sera race gated is her being an elf and not liking nobles and so she could be race gated against humans, I do not see this happening at all. Humans is the most played race in the series at 80%, they are not going to exclude the most played race, plus like Dorian Sera comes off as the type who wouldn't care about race and even if the human inquisitor is a noble she would at least get to know them before making a judgment on them, I think she is the type where she would think your actions speak louder than words. She also doesn't like nature so that could mean she has no love lost for the Dalish and with her being a member of The Friends of Red Jenny she has had to work with humans before and who's to say she didn't have a past relationship with a human member?
Potential Romance Options
Vivienne- With her being the only female left I think its almost 99% possible that she is one of the unannounced romance options. Vivienne comes across as many have stated as uppity, some have called her conceited and even a diva. She comes from a higher order and wants to go higher on the political ladder and so a lower class race liked Elves might not be her thing as human x elf relationships in nobility are seen as a controversial topic, so really I could see her being Bi but only with Humans.
Varric- Based off what we know and if he is a love interest, I could see Varric being straight and only for female dwarves, I don't see him being Bi.
Solas- He is the only one left I could see being a love interest (sorry Blackwall fans), every game has had a Bi elf party member why stop now? I really think the last 2 are Solas and Vivienne, I think he will be Bi and be only open to humans and elves. The reason behind this is that he is an expert on the Fade and from what people have said he would want to be with someone who could dream so he could be with them in the fade, Dwarves don't dream, Qunari I've heard do dream but not like human's and elves do, so I could see him being open to only humans and elves.
My Final Verdict
Cassandra (if gated)- Humans and Elves Only
Cullen (if gated)- Humans and Elves Only
Dorian (if gated)- Humans, Elves and Qunari Only
Sera (if gated)- Humans, Elves and Qunari Only
Vivienne (if gated)- Humans Only
Varric (if gated)- Dwarves Only
Solas (if gated)- Humans and Elves Only
So there you go, really since we don't know enough about the new companions you can't really give a good reason based out of theory alone, I do think Dorian and Sera will be open to any race since they already have a large fan following Cassandra and Cullen could be based off what we know about them, but really to keep the selection at least somewhat equal the two race gated romances need to be Bi so at least they have more choices in the matter over a romance that's both gender and race gated, so that is why I believe the last two unannounced ones are both Bi and are the race gated ones.