Guys I'm expecting the devs to surprise us with this thing this time. I think that because if they were just not capable of adding the other genders, they would already have said it on an official statement...
There is always hope that we go to benchmark and there are both genders!
That being said, another reason why I think this could happen is that it isn't that hard to add new races if you make their bodies look very similar to others (I know that because gear is shared amongst all races, and if you change 1 piece of gear on one race's model, with some exceptions, all the other races will also get the change), so if they truly want to do so, they do have time enough to remove the genderlock, since it's oly headgear and animations.
That being said, I wouldn't personally mind if we couldn't equip headgear or do some specific emotes or maybe even have some pieces of gear look the same, if that would mean getting the other genders added soon.
Anyways, It might be unliekly but there is nothing wrong in hoping i guess!
Here is a version of male viera that seems to be based off highlander and some ppl could enjoy (though I expect them to make male viera more like elezen) enjoy!