Whenever I see these kinds of calculations I just roll my eyes, because video is compressed. There is a very good practical reason why you want 8K. It's the online streaming bitrate! Today if you watch 4K video on Netflix they use 20 Mbps, give or take. That in my opinion is NOT good enough for 4K (UHD). The reason why I am looking forward to 8K is that then they will finally have better video bitrate. So 8K bitrate would be probably be equivalent to reasonable 4K video bitrate.