Support for 4K 60Hz 4:4:4 @ 10 bit is different than 4K 60Hz 4:4:4 @ 8 bit. HDMI 2.1 may not even resolve the former issue unless somebody else has an idea?Not sure. I did get some nice HDMI cables to go with all of my new setup.
http://www.sony.com/electronics/televisions/xbr-x800d-series/specifications
Here are the specs.
Also, when using anythign from PC to PS4 to XB1 S i set my HDMI to be 'Enhanced format' in the settings.
Check this for some more info on the TV.
http://ca.rtings.com/tv/reviews/sony/x800d
Edit:
4K @ 60Hz 4:4:4 8bit is automatically supported by the HDMI 2.0 spec, but HDMI 2.0b makes no mention of 4K @ 60 Hz 4:4:4 10-bit
http://www.hdmi.org/manufacturer/hdmi_2_0/hdmi_2_0_faq.aspx
http://www.hdmi.org/manufacturer/hdmi_2_0/index.aspx