Hello, My Name is Human

[Bonbori]

I wouldn't say "never" but it would definitely require an unprecedented amount of work, meaning they'd have to allocate more budget to it than they did for the Au Ra, and would permanently increase the workload (and thus cost) of developing all outfits from that point on. In order for a dramatically non-human species to be added as a playable option, SE would have to sacrifice something else to pay for all that.

More miraculous things have happened (I mean... Realm Reborn?) but it's hard to imagine SE spending so many resources on something that I feel a large portion of the playerbase wouldn't find terribly appealing. Beast-like races tend to have niche following at best. Even in games like ESO where Argonians and Khajiit are considered absolutely core and TES fans would have lost their minds if they hadn't been included.