The guys we talked to say that even if you want to do the offline rendering you are facing a problem of time, and in Hollywood everything is mission time critical. The basic problem is that it takes a lot of time to render any ray traced scene and we've learned that Cars was the first animated movie to actually use the real ray tracing in full.

Mental ray is one of the best ways of doing ray tracing and Nvidia owns it, but at this point no one from Hollywood even considers this as a real alternative.

They can still get away with the traditional ways of rasterization and light approximation. Photons and Ray casting and something for the distant future.

You can imagine that this means that games with real ray tracing are literally years away.