I guess everyone has their own uses and opinions with these things. For sure, I'm packing up my 3 Sonos Speaker set-up and donating them to Good Will when the HomePods are available to purchase. The #1 problem I have with my Sonos Speakers is having to use the Sonos App to listen to my music, Also, I can't listen to or send any audio from my computer to my Sonos Speakers. When watching movies, videos or even individual audio tracks on my computer, the Sonos is useless. The fact that the HomePod is Airplay 2 compatible is a win-win for me. Nicely done Apple. Just wish you would release them sooner if you're comparing them to Amazon's Echo. Amazon is going to sell a truck load of ECHO products before this thing sees the light of day. Good Luck Apple.
If you have a Apple TV (and Sonos speakers connect to your TV, obviously) you can simply AirPlay to your Apple TV for Apple Music or whatever other app/service you want and it will work perfectly. But you have to manage all multi-room settings within the Sonos-app. Or you could get a AirPort Express and use the line-out and connect it to the line-in on a Sonos Play Bar, Play Base or Play 5 and you can do the same thing.
But one would hope that Sonos will integrate AirPlay 2 into their software/firmware like they recently did with Spotify Connect. That would be really awesome and I see no reason why Sonos wouldn't want to do this as that would make the Apple Homepod less of a competitor as Sonos would be capable of doing all the same things (besides the Siri stuff) all at the same time as it offers all the various other Sonos features that are cross-platform.
In terms of audio playback for videos it's tough. It's hard to get the video/audio in sync. I have tried to use AirPlay on both my Apple TV Gen 4 and my AirPort Express while watching Plex, YouTube etc on my iPad and it's never sync so it's a no-go for me. It works if you AirPlay the entire video to the Apple TV of course, but not when playing back video on my iPhone or iPad while playing the audio using AirPlay. One would hope Apple is capable of nailing this with the Homepad and AirPlay 2, but I have my doubts.
When it comes to replacing Sonos I'm somewhat sceptical. First off, the speaker seems to be tiny. Physics still applies for speakers and I have a really hard time believing Apple is able to put out something that challenges speakers like the Sonos Play 5, Play Bar, Play Base etc.. In such a tiny package. But only time will tell.
And how do Apple plan on tackling the living room? The prototype features no line-in, none at all. How would one connect this to the TV? I for one hate the idea of having extra speakers dedicated to music only in my living room. Apple should, just like Sonos be offering something that is capable of replacing your current living room system. Sonos offers the Play Bar, Play Base and the Play Sub, as well as they give you the capability of adding surround speakers by paring additional Play 1, 3 or 5's.
How is Apple planning to tackle this? If it's wireless only, it will only work with the Apple TV using bluetooth/AirPlay and that won't be good enough as I use other devices other than my Apple TV on my TV so I need some kind of line-in so it can be my TV speaker. Will Apple even try to provide something that supports Dolby Digital Plus surround? Or will they offer up to two channel stereo and that's it? Will they even support TV's at all??
Apple Music only? I can't connect to my iPhone via Bluetooth to play music I bought on iTunes? What the eff?
Of course you can, it will most certainly feature AirPlay 2.
It is not clear to me whether HomePod supports Airplay or not. On the footnotes they say it can deliver music to multiple speakers via Airplay, but it doesn't say if the HomePod can be used as a simple speaker.
I see no reason why it wouldn't support AirPlay 2. Not doing so would be outright stupid.