High-definition television uses 1920x1080 (2K) resolution. The hyped about Ultra HD television coming to stores soon uses 3840×2160 (4K) resolution. But plans are already underway to go beyond that - all the way to "Super Hi-Vision" 7680×4320 (8K).
Sony is reportedly developing production equipment to support 8K, approximately 16 times the resolution of today's HD, to have it ready in time for the Japanese broadcast of the Tokyo Olympic Games in 2020. Sony is recording the upcoming World Cup Final 2014 in 4K, which many see as a big first step in Ultra-HD broadcasting.
But 8K is seen as the holy grail, a resolution so high that even the biggest possible display a household can practically use (100-150 inch) you won't be able to see individual pixels unless your within a few feet of the glass. The format also boasts 22.2 multichannel surround which reproduces sound in three dimensions.
Source: HDTV Test