Even a 3 way SLI GTX 980 ti will not meet these requirements. Remember, that 90FPS figure is a minimum. How many games have you see with great visuals, that can also hold a 90FPS mimimum.
VR will not be too appealing if visuals overall have to be toned down significantly in order to ensure that high end systems can maintain a high minimum frame rate.
I have used the newer oculus rift (demo) and while it is a cool experience, it loses the cool factor really quickly since the demos use dated graphics on a platform where visuals play a more important role.
With non VR, it is easy to accept non visually stunning content, especially of the gameplay is great, but with VR, you can't really skimp on the visuals, or you end up with an experience that does not last much beyond the initial novelty, as they are needed to maintain a more true sense of realism in terms of the feel of the visual experience.