I still have one. A few years old but still works, rock-solid and what I love best is the form-factor: unobtrusive, in fact, totally hidden from view.
Google inexplicably killed the Chromecast Audio as well, and it was an absolutely perfect device for a very particular niche (streaming audio to an old stereo/amplifier without needing a permanently connected phone as is the case for Bluetooth).
I hope mine still lasts for a long time (I believe there are some Google-signed certs on it that might expire some day?).