I'll probably need to invest in an 8K screen before too long. Not necessarily because I want one, but because that is likely the way that testing will go on the high-end before too long.
Nvidia was already pushing 8K with the RTX 3090, and as tech like DLSS gets better and GPUs get more powerful, 4K may not be a good enough test for uber-tier GPUs before too long.
When 4K becomes more commonplace, 8K will become the new 4K. Screen-wise, I will be strictly limited by cost and the size of my office/gaming space.