alt Hacker News> we could have baked address extensions into the existing packet format's option fields and had a gradual upgrade that relied on that awful bodge that was (and is) NAT
We did and do have this. I wrote about the option fields part in [1] but we also have NAT as part of the migration, in the form of NAT64.
Not only was doing these things not enough for us to be done by now, they weren't even enough to stop you from moaning that we didn't do them! How could anything have been good enough if these are the standards it's judged by?