While i'm a videogamer at heart, I have tried and have no interest in gaming on the ATV. What I would like though is more speed as my 4th Gen is getting a little slow pulling up an app. I'm also been for sometime having a delay on my remote where I need to wait a full second before the 2nd click registers. Not a big deal really but kind of annoying. I don't have that delay using the TV remote app on my iPad so it's probably a software thing.OTHER THAN HDMI 2.1 there's very little that the Apple TV needs.
HOWEVER... With the launch of Apple's gaming subscription, there is a huge argument that we'll see the A12Bionic chip put in it. No interest for me as i've never played a video game in my life!
What would you like adding to Apple TV? I guess for me, iTunes offering all of their catalogue in Dolby True HD would be very now! That's my only criticism of iTunes - the volume is so low on their films! If i'm watching on my Mac, you have to have the volume on max to get a hold decent level. It's strange as Apple likes to think that it's the best with everything and yet, it's seriously bad in this area!
In my opinion, the gaming service with the Apple TV will be no match against an Xbox or PS.