Nobody is in a position to EOL v4. We'd need a planetary government for that, and we don't have one. It would be nice, but we have to work with what we've got and not what we wish we had.
I run my desktop with no v4, so it's clearly possible to push handling for v4 out of your network. You could outsource it to somebody else even, for example by using one of the DNS servers listed on https://nat64.net/.
We can EOL things insecure ciphers and old operating systems without much issue without a planetary government.
The migration strategy for ipv4->ipv6 was just so horribly conceived that we'll be running both in parallel for decades.
TBH I think it would have been better if ipv6 was named something else entirely. Running TCP and UDP in parallel doesn't raise any flags, but running two versions of the same protocol in parallel is strange.
Can we? People continue to use both even after newer versions are released.
I don't think it was horribly conceived. I think it's close to the best we can do given the constraints we're working under. These constraints include the fact that there are millions of networks being run by millions of people and nobody is in a position to force all of these people to stop using v4.
I run my desktop with no v4, so it's clearly possible to push handling for v4 out of your network. You could outsource it to somebody else even, for example by using one of the DNS servers listed on https://nat64.net/.