See from the point of 6m 45s in the video in the link. It briefly explains the new zones feature.

https://www.sonos.com/en-us/shop/era-100-pro

So its Named Groups, which we already have, that can be grouped with other groups or speakers. Of course Groups used to be called Zones back in the day, which is why the original devices were called Zone Players.

Progress. Hmm.

The Zones mentioned strike me as being more of a permanent thing - somewhere in-between ‘grouping’ and ‘bonding’. That’s just my own thoughts however and as you mention the Zones can also be ’grouped’. Useful for business environments, I guess.

Looks like it’s a way of creating a ‘super’ stereo pair… so you can have say 6 speakers bonded together as Bar, 4 bonded as Foyer etc. You can then group these new zones as before. When I say stereo pair I use that only because that was the only way before to get more than 1 speaker in a room working together. I doubt the sound would be stereo… 

More interesting perhaps is the power over ethernet… I can see that being useful in homes too… and it carries data, so probably more reliable than some of the newer WiFi routers attempts at ‘improving’ home WiFi…