Yes if they’ve lasted decades thats their job done

No it means they’ll essentially last indefinitely, unlike BT buds.

Now people are buying usb C headphones and there is no need to continue to support decades old standards

No, what’s happened is that we went from a single open standard for audio jacks to competing standards. And gained nothing in the process.

The ewaste from a pair of headphones is tiny so its not worth fretting over.

It’s not a pair of headphones, it’s millions of audio devices.