This concept would also include the sort of stuff that people are wanting to be able to build tiny houses. Stuff like bunk beds, all in one bathrooms and all in one kitchens.
Logistically, most of the animation for an all in one bathroom is already in the game, it'd be much like what is used for the wardrobe. The only thing that would need to be added, is steam coming out of the vents, and whatever noises that sims already make while in the shower.
Same with the all in one kitchen, the animations are already there, it's just a matter of having sims do it all on the one kitchen appliance.
Which then leads to only bunk beds needing new animation.