Amazing Workaround For Mac
From what we know of Airplay 2, will it be possible I'll be able Airplay the same music to all of my Sonos speakers, along with the speakers my Apple TV is connected to? This would be an amazing workaround to not needing to buy Sonos' $300 device that lets you use your own speakers to stream Sonos music. Seems to indicate it but they could misunderstand: 'Furthermore, Apple has suggested that whatever speaker is connected to the Apple TV, be it a soundbar or speaker system, that would automatically become a de facto AirPlay 2 speaker.' From what we know of Airplay 2, will it be possible I'll be able Airplay the same music to all of my Sonos speakers, along with the speakers my Apple TV is connected to? This would be an amazing workaround to not needing to buy Sonos' $300 device that lets you use your own speakers to stream Sonos music.
Seems to indicate it but they could misunderstand: 'Furthermore, Apple has suggested that whatever speaker is connected to the Apple TV, be it a soundbar or speaker system, that would automatically become a de facto AirPlay 2 speaker.' Click to expand.I think you misunderstand. You won't be able to AirPlay to Sonos speakers.

Think of AirPlay (and AirPlay2) in terms of sender and receiver. The AppleTV can be either.
If you have a speaker (such as the HomePod) that can receive AirPlay audio, the AppleTV can be the sender and send audio to it. Or, if you have the AppleTV plugged into speakers with a wire (such as a home theater system), then it can receive AirPlay audio from another sender such as an iPhone app or Mac app.
Sonos can't ever be a receiver nor a sender for AirPlay by itself. The only way a Sonos can receive AirPlay is if it is connected, via aux, to an AppleTV or an AirPort Express with a cable. I think you misunderstand. You won't be able to AirPlay to Sonos speakers.

Think of AirPlay (and AirPlay2) in terms of sender and receiver. The AppleTV can be either.

If you have a speaker (such as the HomePod) that can receive AirPlay audio, the AppleTV can be the sender and send audio to it. Or, if you have the AppleTV plugged into speakers with a wire (such as a home theater system), then it can receive AirPlay audio from another sender such as an iPhone app or Mac app. Sonos can't ever be a receiver nor a sender for AirPlay by itself.
Changes made from version 2.0.1 to 2.0.2: • Fixed an issue that caused software update to fail for certain nuvi and StreetPilot devices on PowerPC Macs.
• Fixed an issue that caused downloads to fail over a slow connection.
Workaround Examples
The only way a Sonos can receive AirPlay is if it is connected, via aux, to an AppleTV or an AirPort Express with a cable. This is just a guess based on the little information that's out, but i think. Airplay can send to sonos, but sonos can't send to airplay. You won't be able to use the sonos app to send to the aTV also meaning if you use alexa to control sonos, you can't send to airplay also if you have an audio input sonos, like a playbase, playbar, or connect. You won't be able to send that audio to airplay devices. But you will be able to use use your aTV, home pod, or iOS device to send to any combination of sonos, appleTVs, and home pods, as well as any other speakers that come out to support airplay 2.