I'm really interested in the technical side as I was under the impression that the OG PS4 only had the original 10Gbps spec of the HDMI 1.4/2.0 PHY, which tops out at like 24 FPS 2160p w/ 10-bit 4:2:0 when you have HDR metadata. 10Gbps can't even do non-HDR 2160p60 w/ 8-bit 4:4:4/RGB color as it doesn't have enough bandwidth (4:2:0 works though).
I have heard, however, that the HDMI chip in the PS4 is a custom DSP job from people in a position to know such things and I guess the chip in the OG PS4 can be pushed to do 18Gbps of HDMI 2.0b?
I'm also curious on the object-based audio side with Atmos and DTS:X to see if there's any kind of channel and/or bitrate limitation. Might even be a complete lack of support like the Phat PS3 and bitstreaming TrueHD/DTS-HD.
Though not explicit mentioned, I'm going to assume Rec. 2020 and DCI-P3 color space will all be there on all hardware revisions, regardless of resolution, provided the display conveys support in the EDID data. Probably some OS-level 3D LUT color mapping too, but who knows.