That'd generally require a re-working of the races in the game's code. Right now even adding a race via a mod is a painful process considering how many places you need to modify so that the new race can actually be used. Not sure they plan to do that. I know they're re-working the events system, but not sure on races?

I do dream of a more generic "Race" class which then has various attributes and ability for wider variety of attributes that can define their own flavor text for sexual interactions. Plus could then allow defining races via json or some other format, and yeah could even have an in-game editor to create/save/share races. That would however require a re-work of the races and all the sex actions.  This is something a mod could technically handle, but it'd be one massive mod heavily modifying the game.