Well shit, I have a couple of BNIB Chromecast audios lying around for years that I've been meaning to put on eBay. Hopefully they fix them so they're not paperweights.
Comments from Google accounts on Twitter and Reddit say they are working on a fix.
Hey there, we're aware of an emerging issue impacting Chromecast 2nd gen and Chromecast Audio devices and are working on a fix. Do not factory reset your device - we will keep you all updated when the fix rolls out. If you have already factory reset your device, we will provide instructions to set your device back up as soon as possible. Thank you for your patience.
I bought a Chromecast Audio right before they were discontinued, trying to get in while I still could. It's the only way I cast to a wired speaker system from the 80s that works reliably.
I loved the convenience but I will not go along with their cash grabs. I will not buy their new product because they took away the old one that was still working.
They were discontinued because they lost a patent case. This one I won't blame on Google... cept maybe for their legal team not flagging it for patent infringement.
I have to think there's some project out there where you could plug a 3.5 to RCA adapter into a Pi and use it in a similar fashion. Maybe would need a bridge app from the 'cast' function to connect to it, but I expect not impossible.
There's nothing else like the Chromecast audio, and it's a crying shame that Google discontinued them. I have four and rely on them every day. I sure hope they will fix this issue.
It's possible to encrypt traffic without a cert that expires.
I don't know much about how Chromecast works but my bet is that it's like a hacked together lighthttp or nginx server, which is why it needs a SSL cert renewal.