Yeah, I think diminishing returns kick in at some point.
Going from 1080p to 1440p feels like a huge improvement.
Going from 1440p to 4k (aka 2160p) is a little bit sharper.
I don't think the jump from 4k to 8k will improve things that much.
I can tell the difference between 1080p (or upscaled 1080p) and 4k on a 50" screen at "living room" distances, but it's nowhere near as obvious as SD to DVD was.
At "laptop" screen distances the difference between my Retina display and non-retina external monitors is quite noticeable; so much so that I run 4k in 1080p mode more and more.
8k is going to require those curved monitors because you'll have to be that close to it to get the advantage.
> I can tell the difference between 1080p (or upscaled 1080p) and 4k
Are you talking about the resolution of the video or of the screen itself? Lower resolution video looks worse also because of the compression. I saw bigger difference from video compression than from screen resolution. E.g. good 1080p video looked better than bad 1080p video on any screen and resolution.
I have a 43" 4k monitor at ~1m distance and when I use the computer set up with 100% scaling it looks bad, I see pixelation... and "subpixelation". On a different computer connected to the same screen but something like 150% scaling it's like night and day difference. Everything looks smooth, perfect antialiasing.
This is the money picture [0]. Above a certain distance any improvement is imperceptible. But don't compare compressed video on a screen, it will add quality issues that influence your perception.
Going from 1080p to 1440p feels like a huge improvement. Going from 1440p to 4k (aka 2160p) is a little bit sharper. I don't think the jump from 4k to 8k will improve things that much.