Ehh, There's a gradient to how popular something can be expected to be. Highlander tall, updated, full on Miqote (Anime girl face and all) with fur patterns and full head support? Would legit be one of the top played things in the game. On the other end ... these buff af beefed out "Dudes with boobs" I see in the fan art? SE might as well set that money on fire.
I guess I should establish what I consider "Popular", right? Looking at the numbers, any female as popular as Middie Females. So about 52k players. Using that as a base, there's only 3 unpopular female types in the game (Highlander/ Elezen/ Femroe in that order, with Femroe waaaay down there. You can add all 3 up together, and they're still not as popular as Middie females).
The secret to female characters is that, beyond all the concepts and such, people really just want fun dress-up dolls. People aren't getting tired of any niche (I'm sure a race that looks like our lil blue bird child would be hella popular, just like a doggy Miqote race or Mouse ear Lalas) nor is making everything smoll the only way to make something popular. Viera Females are nothing if not a full-blown hit popularity wise, and literally every female from Femroe to Miqote took a numbers drop from converts when they came out for this reason. Could they be MORE popular if they were shorter? Sure, I guess. They could also be more popular if they could wear headgear, 60k+ are great numbers regardless.
Anyway, never been one for the thought of "If it's not first, it's last". Sure, realistically the chances of them making them in a way that would make them one off the top played females are not high ... but I still know there are many ways to make them decently more popular than those 3 female races or Male Hrothgar or even Middies, so I'd never wave the white flag on em, gotta wait to see wtf they look like first. Hell, I know Male Hrothgar would be more popular if they weren't wide af and stood up straight.
The thing about Khajiit is that ES basically suffers from the ol Western curse of having no/ a boring af artstyle, which FF14 doesn't suffer from. When I look at this, all I see is a realistic cat head on a reg human body. No style, no expressive features, just a reg real looking cat head. The bare basics of "furry race with a not jank body". I know too much about furry artstyles to think that if that can get a strong fandom then more interesting styles can't. Like, after seeing that banging job they did with loporrit, I'm 100% sure that they can make a hella cute and appealing anime cat face if they wish.A full on furry femhroth just won't pull in the numbers something like a Khajiit in ESO would.