So on DoLP, I tried a game where all the named NPCs and random NPCs were all futas (NPC generation is 100% females with both penis and vagina), then played as a futa myself. The idea of this round was to see if anyone still cared about whether you're futa or not if everyone's futa and such. Unfortunately though your character still cares about whether others know they're futa or not, and despite NPC generation is set at 100% female, you still get in trouble for entering the male section of the School's Pool Changing Rooms when it has students in it. I guess in such a world there are still male students, just that they're so unimportant that they have faceless mob status? Though I didn't test to see whether the NPCs that spawn as part of a potential gangbang event if you enter the male changeroom enough times like that would turn out to be all futas anyway.
I wonder if it'd require the DoLP devs to change some core coding to change this sort of thing (and breaking things in the process), like having a world where the PC is instead afraid of being found out if they're the only male/female in a world of consisting of those of the opposite gender, or if they are the only pure female in a world where all females are futas. That said, the current NPC futa implementation was probably just slapped on as a 'why not' or as an absorbtion of the existing Herm Mod, considering that unless the PC is just that flexible, they're able to get penetrated vaginally/anally by a NPC while the PC uses their feet on the NPC's vagina. If it was the thighs I can picture it better (the NPC rubbing themselves against your thigh as they penetrate you), but well, I guess all those Yoga Lessons at Charlie's must be paying off.