iTunes currently (July 2018) already offers a few movies ready for Dolby Atmos. Real start seems to be scheduled for autumn.
1. When will be HomePods updated for Dolby-Atmos pairing?
2. How many HomePods do you need at least? Will it be possible to depict a spectacular scenario based on 3 or 4 HomePods?
HomePod
1. It is unlikely HomePods will support Atmos as a stereo pair, and as Atmos requires bouncing or direct audio from above the listener, you would need at least an Atmos sound bar. HomePods are designed for music playback, not movie playback, even though they can be used as such.
You would need at least 9, including two in your ceiling, plus 2 subwoofers to get really spectacular scenarios.
I have never heard of any plans for the HomePod to be Dolby Atmos compatible or even Dolby 5.1
HomePod Update for Dolby Atmos
