8k is actually 4 times the pixel resolution of 4k.The video capabilities don't impress me simply because I don't do serious video. However, it will sell cameras. The Olympics was planned to be broadcast in 8K, so all the manufacturers are getting on the bandwagon. I expect that the current slow camera market caused Canon's sales department to ask for speciications that would meet what they expect from competitors. They all pretty much know where the industry is going. Obviously, there is finally some new technology going into sensor manufacturing. Will it improve high ISO low light noise? I'd expect a incremental improvement, they need to portion improvements out over time, its just how things work.
8K is not a huge improvement in resolution, resolution does not double. Whether people can see it, or even find 8K source material does not matter. Most TV sets are now 4K capable, they have a good picture, so I can't complain. As to editing 8K with my computer, I think it would be a pain, but the technology is there to make it happen.
So, I'm interested in what still improvements I'd see over my R and my 5D MK IV.