... meaning I still have to have a public IPv4 address (or many) for them to connect to, and I have to install a NAT system that is, if anything, an even uglier, more complicated kludge than plain IPv4 NAT.

And I still don't get any-to-any connectivity with the IPv4 people, which is what you need if P2P is going to be seamless.

You're never going to get that. There isn't enough v4 in the world for that. That's kind of why we're doing v6.

You don't have to install NAT64 to connect to v4-only hosts -- you can run dual-stack, and use your existing v4 setup to reach them. NAT64 is just what you do when you want to turn off v4. You said in the post above that people running networks should have been told they had to change things, so you don't get to whinge about needing to do it yourself.

Also, you don't need to have a public v4 address for v4-only people to connect to you. Reverse proxying is a service you can pay for, and only the people running the proxy need v4. CloudFlare do this (for free, even, depending on what you're doing).

In fact the same is true of NAT64; set your DNS server to e.g. 2a01:4f8:c2c:123f::1 and away you go.