HOLD off on those Top end Graphic card purchases a bit.. until the dust settles on this one..
The 2080Ti, for example, shoulllllld get 2.1 support, but we don't know for sure atm because testing is not finalized.
Currently
HDMI 2.0 (18Gbps) can not support 10bit/10bit+ 4K HDR with 4:4:4
It can only do 2 out of 3 of the following features simultaneously, all 3 requires ~23Gbps
4K (3840x2160)
4:4:4 (chroma sub-sampling)
HDR (10bit, 10bit+)
the Upcoming HDMI 2.1 will feature 48Gbps which will be able to do All 3 and more.
2.1 will do:
4K 120hz HDR (10bit) 4:4:4
8k 60hz HDR (10bit) 4:2:0