So, my opinion is that the bottleneck for deploying IPv6, and therefore
getting rid of NAPTs is the cost of IPv6 address space.
it's one of the potential bottlenecks. certainly not the only one,
probably not the largest. folks still have to learn about the
differences between IPv4 and IPv6, and applications using IPv6
have to be deployed. those are significant bottlenecks.
note that 6to4 makes the cost of getting a good-sized chunk of IPv6
address space roughly equivalent to the cost of getting a single stable
IPv4 address.
Keith