I don't think it's supposed to be any version specifically.. my guess is there's a flag and bits and pieces of it exist in all 11.x versions.
Atmos support... and I hate to be a Debbie Downer.. but I am betting it won't come until 12.0. Apple is already tied (essentially) as the most capable streaming box on the market (as there is no box currently that does HDR10, Dolby Vision, Atmos, 24p, etc all in one. and I said box, not shield). At this point they will probably gain more users by focusing on content providing (securing more app deals) and serving (improving aggregation with sports, live tv, and again more app deals). I have no doubt Atmos is actively being worked on... but for 11x I just have to believe they have higher priorities that will pay off better for them. Besides, then it gives them a big announcement at WWDC next year. It also gives them a year to get encodes on the store with Atmos tracks so they can launch with hundreds of titles instead of the dozens they launched with 4K.
just my 2¢
also after a week, I AM a fan of format switching... but I totally get why they left it out and have it turned off by default. It introduces a lag constantly, especially when going from video to menu in most HDR sources. The screen savers coming up when a movie is paused look awful at 24fps (and the UI in general just performs awful at 24fps) Like everything outside of ACTUALLY playing the video is pretty much a lesser experience.
I'd almost wish now (:P) that they just give us a quick remote control option to switch video to a native format, and leave the box in HDR60 at all other times. Auto switching IS better than we had it before.. but it's not quite the seamless experience everyone was hoping for... which now I understand why Apple resisted.