Keep in mind there were a lot of companies, including sonos, who announced AirPlay 2 compatibility. Meaning multi room could be done with a HomePod in the living room, sonos one in the office, and a future beats speaker in the bedroom, for example.
Because HomePod is the only Airplay 2 speaker currently going to be on the market everyone looks to it as the only product, which won’t be true for long.
It will be interesting to better understand just what Airplay 2 can do with Sonos... here is my understanding, tell me if I am wrong...
1. Only the Sonos Play One, Playbase, and Play:5 Gen 2 will be compatible with AirPlay 2. (Play:1, Play:3, Play:5 Gen 1, PlayBar, Connect, Connect:Amp all will NOT be compatible.)
2. Sonos says you "may" be able to use Airplay 2 to control a device which is not compatible with Airplay 2 if it is grouped together with a device that IS compatible with Airplay 2. They haven't committed to this and even then it is limiting obviously.
3. You will not be able to talk to your Sonos Airplay 2 devices with the "Hey Siri" command. You will have to talk to an iOS device, Apple Watch, or HomePod and then use the name of your Sonos Airplay 2 device to control it. For example saying "Hey Siri" to your HomePod in the living room "Play U2 in my bedroom" which has a Sonos Airplay 2 device will work. Actually being in your bedroom and saying that will NOT work, you'll have to talk to your iPhone or Apple Watch in that case. That may not seem like a big deal but it can be a pain and limits you to family members with compatible devices, unlike anyone including guests who can talk to HomePod.
Basically what I am saying is this... Sonos will work with Airplay 2 eventually but there will be significant limitations in hardware and software. I agree, if you have a bunch of Sonos "Gen 2" Airplay 2 compatible speakers then it is nice to be able to at least work them into your Apple Airplay 2 system, just don't expect that by buying a Sonos Play One speaker today you will be getting the same seamless Apple Music experience that HomePod gets you when Airplay 2 launches.