Meanwhile ...
This is interesting
https://www.theverge.com/2017/8/5/16102320/apple-tv-4k-hdr-support-rumors
Most UHD HDR TV's have the apps for UHD HDR content (Amazon TV, Netflix, YouTube, Google Play, etc)
but its the usual balkanazition of content over providers, so Apple may bring something to the table.
Somewhat late to the party, hardware wise (cf Roku, NVidia Shield) but standards are evolving so maybe later is better.
Compare to Amazon Fire TV, that although it does 4K , no HDR because HDMI (the port spec it shipped with)