I know it's not viable, but yet I've always felt IPv6 would have been a nice opportunity to extinguish port numbers. Just give each service its own IP from the /64 the host was allocated.
Then you could have one DNS entry per service. That would have been perfect for residential IPv6 with dynamic prefixes, which require dynamic DNS anyway.
Ah I get what you mean now. For the most part I just don't care about similar things running on the same port, because I've got many thousands of addresses I could just choose to listen to. I can have tons of different things listening on :80 or :443 or whatever on IPv6.
Then you could have one DNS entry per service. That would have been perfect for residential IPv6 with dynamic prefixes, which require dynamic DNS anyway.