Well a VR Observer mode would be a really nice thing for the sims. Just snap down into first person mode and walk around your sims house and watch what they are doing and what you have created.
A complete VR Mode where you play the game in VR would be a total nightmare and cut alot of features.
And VR in general is a thing than does not belong in sims 4 and needs a sims 5 that is designed for it from the ground. Sims 4 world is too lacking for vr, there are no real ceilings and roofs so you dont stare into the sky when you look up, and textures and details are too low to go up close all around, also the ai would need an big improvement to act on its own without frequently needing a babysitter.