The consumer version of the Oculus Rift (CV1) does not represent the bare minimum for acceptable VR. In my opinion, DK2 was close in many ways. With a little better ergonomics and maybe less screen door, they could've sold DK2 as CV1, and would've if it hadn't been for the FB buyout. The 75 fps of DK2 is plenty sufficient thanks to the low persistence. CV1 is going to be 90 fps which is overkill to be on the safe side in my opinion.
I think Playstation VR can definitely be lower quality than CV1 in many ways and still be a great success.