HDMI 2.1 is a hardware update, it can't be done with a firmware update. It's possible Sony's followup to the Z9D, Z10D may have HDMI 2.1, but it won't launch till Q4 2017, same goes for Xbox Scorpio, possible for HDMI 2.1 Q4 2017, but no guarantee. Only thing that is a promise is next year there will be lots of products announced at CES. HFR is HDMI 2.1 2018 models or later only. New tvs, new a/v receivers, new game systems, new cable boxes, new tv tuner boxes, and new blu-ray players w/ dynamic metadata Technicolor HDR (St 2094-20), all of that stuff is 2018, most of it is HDMI 2.1 only. HDMI 2.0a gets 4K @ 60 input/output only. No gaming at 120fps, nothing above 60fps max on a 2017 tv. NFL games will look incredible in 120hz, bigger upgrade than 4K arguably.
That woulld look incredible, I can't wait for the World Cup in 2018.