[WorldMaker]

At that point you just use a much simpler reverse proxy, I think? NATs have to be stateful to operate, but in IPv6 you can do a lot with simpler stateless reverse proxies.

[zamadatix]

NATs in this inbound scenario are most often stateless 1:1 static mappings of the port.

[JohnFen]

For several services, you're probably right. But not all of them. I think.