There comes a point where the eye just can't appreciate more detail. Dunno if we've reached that point yet. Afterall, Apple said their Retina display was supposed to be as much as the eye could detect... and now there's Super Retina or something like that?

I'm certain I'm oversimplifying and confusing issues in my mind, but I also don't think 8K will be in full swing for many years to come, probably, just due to the cost. I'm fully prepared to enjoy my 4K for at least the next 3-5!

I suspect OLED will become much more affordable before 8K does, too.
Just my 2¢.
Cheers!