[ars92]

HDMI 2.0a/b still.

I doubt the revised 2019 Shield - Tegra X1+ that has had a chipset shrinkage, has added anything new tech wise.
That same more power efficient X1+ chipset is also going into the revised 2020 Nintendo Switch.

With power efficiency gains, you also reduce chipset heat output and then you can increase the Chipset clock rates, for say a 25% faster Shield and still achieve the same thermal stability.

The added DolbyVision Profile 5 is a Player-led profile, same as all the other DV 4K capable media streamers.
That can be added entirely in Shield Firmware along with the, mandatory, accompanying Dolby chipset licence.

Improved output Picture upscaling can also be added in revised device Firmware. For years there has already been existing proven upscaling algorithms and code available for that.

The Nvidia (Shield Linux) Kernel guys have been a bit busy, the Shield Pro hardware guys not so much.

Perfectly happy with the current 2015 non pro shield. I've not even made to move to HDR TV and am still on standard netflix plan.
Lets see if 2021 has a revised hdmi 2.1 version but it's seems like overall nvidia don't seem to be too enthusiastic about revising their hdmi version, even on gpu....