if you play the 8k down sampled by your PC's video card to 4k, through your PC display-port uncompressed RGB output, you will at least get 4K color resolution, IE a new chrominance (my made up word) per pixel at 4k res instead of the color being 1/4 resolution which is the standard video compression technique.
Isn't it also that some (cheaper) camera sensors have a 1/4 "color resolution"?
Nope, sadly, this is still in the x264 and x265 standards and many single CCD/CMOS cameras still use the BAYER staggered RGB pixels where the color is still at a lower resolution than the luminance. In fact, to get higher refresh rates above 24hz at 8K using a single display port link, the color is once transmitted in YUV instead of RGB, and the UV color channels are compressed. This also goes for 4K displays at above 90Hz or above 120Hz depending of the display port revision.
Yes, I would like to see 8K at 60hz, but, Youtube doesn't really want to support the required bandwidth and many consumer PCs are just too slow to realtime video decompress that x265 data. Decompressing 8K 60hz is identical to decompressing 4k video at 240hz. My laptop has a hard time doing x265 4k at 30Hz, let alone 240Hz. My top desktop will easily do 4K at 60hz, but 240hz is still a big leap.
Remember, each single 8K frame is 132 megabytes uncompressed. In x265, I can send you an entire 30 minute TV show at 1080p with 132 megabytes. I can send you an entire x265 1080p movie, with surround sound, with just a few 8k video frames.
To decode 8k at 60fps, I need to render 80 gigabits of data a second.
ADDITIONAL note: A deep color 4:4:4 color mode does exist for x264 and x265, however, it is not guaranteed that the decoder side has the memory, speed, or capability of decodeding these extended video modes.