Not to spam, but you can actually see the role of genders and their importance represented in Ancient Deities. Early human civilization used to have Female Goddesses as the most powerful deities because women started out as one of the more important genders. The shift in gender importance is marked by stories of Gods, men, taking power from goddesses, women. And then, in almost a cyclical pattern, women started to regain power in more modern times.
So, the binary between men and women is something extremely ingrained in humanity, another umbrella term like mankind. I doubt it will disappear overnight, and I don't think everyone will identify as non-binary.
I think, when it comes to representation, the most important thing is freedom of choice and having options to choose.
I know that my most important sims I play with wear clothes in the feminine category, but I don't think of the clothes as feminine or imagine the mermen that wear that clothing as seeing it as feminine. Also, I don't imagine it as the same female clothing.
