Actually NHK is testing the broadcastabilty of 8K-live-TV-programmes. Thus, cameras capable of recording this picture qualtity are already in the market.
8K is the resolution of the UHDTV2 format defined in SMPTE ST 2036-1, as well as the 8K UHDTV format defined in ITU-R BT.2020. It was also chosen by the DVB project as the resolution for their 8K broadcasting standard, UHD-2. 7680 × 4320 has 33.2 million pixels and a 16∶9 aspect ratio. It is double the resolution of 4K UHD in each dimension (four times as many total pixels), and four times the resolution of 1080p in each dimension (sixteen times as many total pixels).