Sonos Announcement today 1/21/2020

Ooooh weeee did this kick off some customer hostility.
twitter abuzz as well.  #SONOS
I just took a very brief glance at that thread: wow! 
I guess the BIG question is: will having legacy gear in the same chain as newer Sonos gear kill your ability to get Sonos updates (which are vital to the system working)...
From CNBC:

“Sonos said people who own the older products can keep using the older speaker in their system, but the new speakers won't receive updates either. A spokesperson told CNBC this is because all speakers on run on the same software, so an older one will lag the system behind if it's still in use.

Sonos told CNBC in May it will launch a way for customers to segment the older products into a separate speaker group, which won't receive updates, while another group of newer products will continue to get new software.”

My Android phone no longer is fully compatible as of 6 months ago. So while most companies work on improvements as Sonos should so they could be more compatible with HiRes, they have been working on obsolescence!

I think I have figured out the acronym for Sonos

What will happen is as soon as your music service makes a change and Sonos changes their software to stay in sync your done.  You can proly keep them around for streaming radio.
So will the original Play:1 still receive updates? I’ve only heard about the original Play:5.  
They are sending out emails.  If you have unit that meets the critirea you should get an email.  Even if the product is not registered as they see it on your system.
I got an email and it identified one of the connects I have in the garage and I bought that unit off craigslist.
Nearly all products that connect to the internet require security updates. If the hardware is so old that it cannot remain adequately secure, then it should be replaced. Just as no one would think of accessing their bank accounts on an iPhone 4 in 2020, eventually WiFi-enabled speakers should be replaced. Now, did Sonos handle the public announcement well? No. But as a result of the backlash they will now be supporting their older products much longer than most tech companies do. I think that they had the right motives, they just needed to communicate better.