As with most things in the beginning a lot of low hanging fruit allow for rapid innovation and progress. As things become more developed, progress tends to slow

As with most things in the beginning a lot of low hanging fruit allow for rapid innovation and progress. As things become more developed, progress tends to slow. At that time both hardware and software made rapid progress. I think currently the big change that is happening is path based ray tracing. In the next couple years a lot of mainstream hardware should be able to do it and it makes a big impact on how games look. Apart from that it's just more triangles I guess. We are approaching photorealistic looks and further development will try to run what huge desktop graphics cards can do, on smartphone GPUs. There we have seen actually significant developments in the past 10 years.