DSC 1.2a (Display Stream Compression) in HDMI 2.1 allows for many of the higher resolution/framerate combos with a visually lossless 3:1 compression. Though I've been around the houses looking for absolute conformation as to what degree it is mandatory/optional in any given HDMI 2.1 implementation and if 8K120 + HDR + 4:4:4 is possible. I think 8K60 is standard, but when you start piling in HDR/Dynamic-HD, 10/12-Bit, Chroma Subsampling, audio and other new features it's hard to know what's supported.
Once we can do 8K @ 120HZ with Dynamic HDR in 12-Bit / 4:4:4 / BT.2020 via DSC + Object Audio + VRR/ALLM/QMS/'CC', then the rest is gravy imo..... outside of VR, there's perceptibly nothing more to be gained for games, movies and tv on a single conventional display.