I would like them to expand the use of procedural generation.
...Most prominently, to achieve individual variation among zombies. Call it random character generation, to complement random world generation. Even a new player that stops playing after their first Blood Moon sees far more zombies than there are zombie models. And throwing in more and more whole zombie models isn't an efficient or effective way to prevent repetition.
...But also, to re-implement procedurally generated caves, to create spaces with replayability within all that 3D voxel space underground. RWG is interesting to an explorer, in part because we don't know where a road will go and what's connected to it until we traverse it. So it should be, below the surface.
Given what TFP have already shared about the story (the White River settlement and the Duke vs. the Cassadores and all that, as discussed in dev videos), it seems certain that they'll at least attempt to have factions. It could be an idea that falls through after they implement it, like crafting grids and minimaps and so many other things. But surely they want to give it a try first.