If the customer sees an IPv4 WAN address in the medium distance future, it's likely to be a private address. Many ISPs are going to do "carrier grade nat", whi

If the customer sees an IPv4 WAN address in the medium distance future, it's likely to be a private address. Many ISPs are going to do "carrier grade nat", which just means that the NAT your current router is doing will be aggregated at the ISP. Your router will be more of a simple bridge device. (It's bad to perform double network address translation of packets, and the relevant DS-Lite rfcs discuss this). I think this will be the tipping point where I start seeing a v6 address as the first class citizen. When I have to start bugging my ISP for a port mapping, I will prefer to just have the entire session occur natively on v6 because it will no longer be the toy, it will have graduated to the tool.