That changed (ahm.. will change) with ipv6. I was surprised to see that I can reach residential ipv6 lan hosts directly from the server. No firewalls, no nat. This remains true even with abusive isps that only give out /64 blocks.
That said, I agree that peer to peer will never be seemless thanks mostly to said abusive isps.
That said, I agree that peer to peer will never be seemless thanks mostly to said abusive isps.