While I admire the enthusiasm I don't think it's that deep lol, besides it really isn't a threat to no one's existence because there are shit load of colonies from the various races, I think only the Slyveren is the only (sapient and UCN acknowledged) race that is stated to be in a "tight" spot because Galotians took a lot of land from them iirc.
Besides, modding exists so if they want they can look like a diferent race, and half-breeds produce "full" members of the species anyway so if a half human bangs a "full" human then the result will be a normal human baby, so yeah the chances are slim.
Riya's racism is more out of Humanity Superiority rather than xenophobia and general fear of aliens, she is racist because sees humans as the superior master race compared to the Ausar, Kaithrit, and others who she sees more akin to wild animals because they are "inferior" she loses her shit when Greence gives her a coal on the Christmas event and starts malding how they are jealous because she is perfect and how humans are better, she is just racist just because.
Or satisfy someone's raceplay kink -- fuck if I know.
Honestly i feel that, ironically, Riya isn't really that and in my eyes I see her more of a degradation kink rather than race-play.
While as we have been talking about this biatch for like 2 days now, her content for me feels much more degradation than race play, though there are some variations it's so small it's quite irrelevant, in fact I think they only change "bitch/slut" to a slur of the race you are playing (Pussycat for Kaithrit, Slutpuppy for Ausar, so forth), it only really goes more on race play territory on her dialogue when you are pregnant but it's mostly just that.
can we turn males into futa?
Hmm... I actually don't think there is a male character that you can turn into a futa! outside of Ben/Bess who can get a dick as a girl or a pussy as boy there isn't really anything.