I think diminishing returns limited the impact from all consoles after the PS360 generation.
There won't be any more generational leaps as mind-blowing as we had each cycle from Atari 2600 to PS2.
Are you ready to die on that hill? Because there will. I have always hated the "diminishing returns" frase, cause it's so easy to throw around as a layman term.
When you know what to look for, you will see the cycles. BUT I know what you mean.. the jump from crude pixels in Quake to hw BF and AA had an instant impact on gamers. This was in the advent when 3dfx cards hit the market. Simple stuff done in hw, with a huge difference on screen. Big return for the consumer.
The quantification of graphics should always be compared to real life imho. And with that we know we have a long way to go.
For each stride in graphics the more important the details become. RT will go along way of making things more true to life. Full path tracing are still some years away, but when it hits and the hw is able to cope, a new paradigm will start.
There will always be opportunities to do something better than before. The devil is in the details.