Even with IPv6, you're still in scenario 1 from my list. Also, using it would really only help with carrier-grade NAT. Someone with the amount of skill needed

Even with IPv6, you're still in scenario 1 from my list. Also, using it would really only help with carrier-grade NAT. Someone with the amount of skill needed to setup a server probably has the skill setup port forwarding and dynamic DNS on their router. Which reminds me of the DSL modem/router combo my roommates had gotten in my first apartment before I moved in. The router was MSN and had no local configuration page, all configuration had to be done through some external Microsoft server that didn't work by the time I got there (so I could never do any port forwarding).