If single core performance can match a 9900k at 5ghz ill bite on a 16core chip.
While the 9900k currently is amazing for fps/frame times in games once you put it under encoding load while gaming on the same pc it does start to sweat a bit.
8 core is nice for encoding/streaming on the same pc but not quite enough for flawless experince. 16 cores might bring that. However nvidia revent software obs improvement to NVENC is really killing the need for x264 encoding
Game streaming reviews I will be watching extremely close.