We hit diminishing returns a while ago. It will be much harder to find improvements, both in terms of techniques and computation.

Consider that there is ten years between Atari Pitfall and Wolfenstein 3D, ten years between that and Metroid Prime, and ten years between that and Mass Effect 3, and then about ten years between that and now. There's definitely improvement between all those, but once past Metroid Prime, it becomes far less obvious.

We've hit the point where artistic style is more important than taking advantage of every clock cycle of the GPU.