Well the rumours here suggest a faster chip and FaceTime camera.
Facetime camera in the box would be terrible except for those people who position it immediately above or below center of the TV. All other places that people put them would result in those on the other end seeing you not looking back at them.
If you don't know this by just thinking about it, fire up continuity camera on your phone or tablet and put it where you would like this new AppleTV to be located. Then look at the view others would have of you.
if you want to do this even simpler, turn on the selfie camera on your phone, sit where you would normally sit, extend your arm and align the phone camera between your face and where you store your AppleTV. Now look right at your TV screen as you would in a FaceTime call this way and shoot some selfie video of yourself. Then watch it to see what the other end would see.
For example, if your AppleTV is stored well right of your TV, a FaceTime camera in it while you look at your TV screen would make it look like you are looking far LEFT of the people on the other end.
And then there's the people who store their AppleTVs vertically and fully behind their TV... or in a cabinet.
To scratch this itch, I think a much better solution would be a revival of a "normal" USB port on AppleTV, so that people could get a TV camera (that mounts on the top, center of the TV and run the USB cord to that USB jack). OR create a dedicated continuity camera that is maybe powered by a USB jack in the TV already.
Why not "just use my iPhone?" That works if you are single, living alone... but otherwise robs those of FaceTime capability when your iDevice is out of the home with you. A dedicated camera that stays with the TV & AppleTV seems the very best way to cover this want.
My guess is next AppleTV hits NEXT year or two... not soon.