I image they will be much sought-after, unless you are suggesting they are being bricked

Even if they don't brick them explicitly they will no longer provide security updates for them.

I'm on the same boat, smart TV has never been online, all content is just cast from media server/phone/tablet straight to chromecast. It works, no fuss, glitch free, and of course they will kill it.

Even if they were to provide security updates, a few platforms no longer work with them. At the very least, now Disney+ refuses to stream to my original chromecast dongle.

My og chromecast frequently crash (I suspect due to running out of ram when casting contents) so I ended up replacing it with the chromecast ultra. The og chromecast is still usable if you can tolerate the crashing, but I imagine it's going to get worse as developers keep updating their cast players (basically a webpage that plays video) with new features that consume more and more ram.

I'm still disappointed they killed the Chromecast Audio... have one uptairs I use regularly. Would have bought a couple extra had I known.