bitcoin never stops supporting old things... if too many clients or relays support something it's out of the question to stop supporting it
Drafted another NIP, this one is for helping NIP drafters draft NIPs
Discussion
That's a valid position, and maybe the only one that will work. But what if 100% of clients and relays published support for the old standard? We could in theory successfully deprecate. I'm not sure it'll work in practice, but that can only be discovered by trying it out.