I have yet to see a game I would call convincingly realistic looking. It is all too easy to pop in stuff that tanks your performance, and a lot of development time goes to balancing, restricting, and simplifying things, to make games render at decent frame rates. (And then, just wait until raytracing becomes more prevalent.)
What I could see taking load off of one's GPU, is cloud rendering. Latency is a major issue with that, which is doubly problematic with VR, but maybe it could assist the local host, by "pre digesting" some things that you'll use over several frames,.