8K should become the standard format for the late 2010s, but not even the 4K by 2K is coming anytime soon. Double the frame rates and dual terrestrial lines to transmit signals all sound good. Screen size is important, but of course it needs to vary and adapt as mass-producing 10 billion or more 8K monitors and TV's will prove too costly especially if the consuming population replaces a unit every six month.
Though it is 16 times the resolution of the 1080p HDTV, we have had 2560*1600 30-inch computer monitors for long and a cheap 2012 Mac Book Pro laptop has a 2880*1800 15-inch display. 4320 vertical pixels are just a little more than twice as many as 1800 vertical pixels. But it's all about broadcasting standard for national broadcasting companies which is extremely conservative (and backward however leading in available technologies.)