Short of something more problematic than ray tracing coming forward in gaming, I am thinking that in three generations of video cards, it will be trivial for a modest video card to drive a 4k game at 180 fps. So, someone will have to come up with the next eye candy need that will require ever more powerful graphics cards or in 5 generations integrated graphics will suffice for your average gamer with most of today's eye candy on full show.
I am at the end of my vision capability at 5120x2160 on a 40 inch monitor, so smaller pixels is not really an option. It already covers the vast majority of my direct vision and some of my peripheral vision. While some games benefit from apparently 600 frames per second, and some people vision is definitely better than mine, there has to be a point at which diminishing returns become non existent returns.
Of course, I was mostly happy with my 1080p for quite a while, but I never felt it was optimal. I am pretty close to feeling that monitors are near optimal in many ways, even if no individual monitor yet hits the perfect yet.
What kinds of technology would be good for driving more computer power?
Near Hemispheric monitors with the same pixel density as current high density monitors with a spherical 800R or 1000R would give some serious ability to feel part of the environment depicted. That could drive pixels up 6 or more times 4K.