[noggin]

My guess is that the nVidia Shield may support whatever flavour of HDR Netflix uses, and assuming your TV does too then Netflix may well deliver HDR on the Shield. At the moment i suspect the only other route to HDR Netflix will be Smart TV apps in your HDR TV.
My next guess that Amazon Prime HDR will only be available on the Fire TV 2 with 4K output as an external player solution (if any external solution works), with most HDR sets using an internal Amazon Prime app.

Netflix will have both Dolby Vision and HDR10. Right now, they only have Dolby Vision and it is supported only on Vizio Reference/ 2016 P-series UHD TVs. Netflix will include HDR10 within 3 months and I guess the SHIELD may be upgraded to support HDR10 within 6 months. Amazon Prime UHD is HDR10 and is supported on Samsung and Sony UHD TV apps. Amazon FireTV 2 will never have HDR10, it is HDMI 1.4.

Thanks for that. Interesting that CNX are reporting that the S912 AMLogic SoC supports Dolby Vision, HDR 10 and HLG for HDR. (It supports HDMI 2.0 in at least some flavours)

I assume HLG = BBC/NHK Hybrid Log Gamma, which is looking like a strong contender for HDR on broadcast TV (particularly as they have already demonstrated live/as-live multi-camera functionality - which is something Dolby have issues with apparently?) Not a surprise given that the S912 has a transport stream input and so a target market is DVB STB manufacture?

Was absolutely blown away by a demo of HDR on a Sony HDR OLED 'broadcast' monitor that had been shot, I think, on an F65. The details in the speculars were stunning. Street scenes at night had detail in the neon lights (which are normally just a blown-out single colour), and little things like LEDs just looked 'real'. I can absolutely understand people arguing that "better pixels" are more important than "more pixels". I suspect many people will see more benefit with 1080/50p HDR than they will with 2160/50p SDR...