4k / 28" is 157 PPI, which is only indistinguishable at around 2 feet view distance on average. Better eyesight puts that distance further back.

8k at 28" is "retina" at just under a foot.

So depending on how far you sit from your screen PPI can matter more or less to you, but when we finally get 8k panels we should also finally be getting people in retina range most of the time.

8k / 120+hz is the holy grail for me.

Not for a 27” panel and above. 5120x2880/3200 for a 27” is good, but for larger panels (29”, 30”, 32”), an even higher logical resolution is needed.

That’s for 2x scaling, of course, but I don’t think fraction scaling creates a good end result, unless everything is vector, which decidedly, very little is.

This isn't 4K or even 4x HD. There's not enough vertical resolution. Consumer 4K is 2160 vertical pixels. This is only 1600. If you write software for a living, vertical space is precious!

No, it's not. Because a 4K "retina" (aka HiDPI) display is only 1080P. 1080P on anything larger than a 24" screen is a non-starter for me (thanks but no thanks to huge icons on screen). I'd ideally like a 27-30" 8k "retina" monitor (aka 4K useable) with DCI-P3 color gamut. Refresh rate I'm ok with 60hz, but wouldn't object to higher obviously.