[noggin]

4K HDR frankly is a bunch of marketing fluffy and technobabble bullshit if you cannot get properly encoded 4K HDR content in the first place.
Doing HDR right means using 4K HDR Netflix & Amazon Video DRM streaming platforms like the NVIDIA Shield / HDR Smart TV's or a UHD player.

4K HDR itself is stonkingly good when you see it done properly. It is a far more important development, IMHO, than 3D, and eventually will almost certainly - like HD and UHD - become 'the norm' for a lot of content.

However at the moment it is limited - really - to UHD Bluray and OTT online streaming platforms (plus a few experimental broadcasts not designed for mainstream consumption)

One area that IS interesting to consider is shooting HDR content yourself though. Increasingly modern mid-range production cameras are shooting HDR (Sony have released firmware upgrades to add HLG alongside their existing Log stuff that supports HDR) so it is entirely feasible that people will want to play content they have shot and edited themselves within Kodi.

Finding mastering workflows that let you do this cost effectively is still - I suspect - a major challenge - and I suspect HLG will be easier to support at the lower-end than the PQ-based stuff like HDR10 and DolbyVision. This will be a niche requirement...