So the romance thread has cooled off a bit with the whole race restrictions rumor that may be confirmed but I'm starting to think Sera may be an exception and be available to any race, she's the first 100% lesbian party member (Samantha Traynor in ME 3 wasn't a party member) so I don't see them restricting her to just elves, at most I'm hoping she can be romanced by any female race since of right now she is female only, not female elf only but if she is restricted I hope she is at least open to female humans also, though I would be interested in romancing her as a female qunari also.
The way I see it is at most Varric and IB will be race gated. I seriously doubt every companion will be (or even more than half the LI's) will be race gated. Over half will probably be gender gated (straight + gay > BI by numbers, even if we get 3 BI Li's), so adding extra restrictions starts getting too restrictive. They probably only included it for Varric (since he already expressed the fact he is only interested in Dwarven girls, and maybe guys), and IB because of sex scene issues. For the rest they could add reasons why they would want to romance only specific characters, but thats extra effort when developing the character (its adding effort to remove content = no-no).
As Sara is already gender gated I doubt you gals have to worry about race issues as well.