Same things we said in 1999 about 2K...
8K will happen when hardware becomes cheap enough.
I expect 8K streaming to become mainstream as early as 2026.
8K Blu-ray discs could happen as early as 2026. This is assuming that 4k Blu-ray discs and players sell well enough.
I do not see the point in 8K for YouTube or for streaming.
I am perfectly happy with my Full HD TV and I can barely see the difference between it and a 4K TV. I like my 4K 32-inch monitor, but only because I look at it very closely when I use the computer. So, at least for me, 4K makes a real difference when using the computer, and is a nice feature to have on the TV, but the difference is by no means huge.
As for 8K, I cannot see the point. The images will not look any sharper in 8K unless I use a microscope. There are so many improvements in brightness, contrast, color, glare, that could be made that would make much more of a difference. Why focus on resolution alone, just to have the bigger number? An 8K video would require better more powerful hardware, would use massive amounts of data, and would put more strain on the Internet connection, for little benefit. So, why? Just to show off?