At a normal viewing distance a 100dpi monitor is already decent. A UHD monitor is just great. You have to get very close to see individual pixels. I'd say doing AA is no longer required even then.
8K seems overkill for most purposes. Sure, there is a niche that can take advantage of it, but I don't see advantages for the mass market.
Same as with SACD, CD tech is simply good enough for pretty much everyone so SACD never took off.
I write this despite being a high dpi junkie, I bought a ViewSonic VP2290b (IBM T221 clone, 3840x2400 22") back in 2006 and dealt with a huge hassle of 4 DPI inputs for years.