I don't have high hopes yet...
Looking at the way Amazon handles Atmos in the FireTV cube, there are basically three ways Atmos could be implemented:
1) The FireTV decodes Atmos and outputs 7.1 PCM over HDMI (= highest quality or best available quality it is called). Apple could do the same. For me, this is useless, but you get higher quality than Dolby Digital 5.1. Basically it's like TrueHD. Higher bitrate. Why is it useless, Atmos is all about more speakers, even upfiring speakers, to get more sound immersion in the vertical dimension.
2) Same 1), but Apple strips the 5.1 "core" and outputs it via passthrough, so via HDMI
3) Apple offers a higher quality option, but bitstreaming the original audio track (so all Atmos info, so speaker layouts like 7.2.1 (2 upfiring speakers) are usefull.
My bests are on 1)....
(unfortunately)
Interesting enough the sounds options are already different tvOS 12.0 beta:
http://www.avsforum.com/forum/39-ne...22-apple-tv-tvos-public-beta-releases-13.html
but no signs of Atmos..