[betterunix2]

I doubt that we will always live in a hybrid world. IPv4 address space exhaustion is a growing problem and NAT is at best a partial solution. As more ISPs resort to things like NAT64 and 464XLAT the shortcomings of NAT (of whatever form) will become a larger problem and developers will start writing IPv6-only applications. After enough time IPv4 service will become optional, and shortly thereafter irrelevant.