Re: Mapping plan
Don't confuse politicians with common sense (and many of the "Internet Engineers" are politicians).
The people who devised IPv6 were NOT engineers - any sensible engineer knows the KISS principle and would not produce such an overblown structure as IPv6. IPv6 was designed by theorists. An IPv6 designed by engineers would have been an addressing extension of IPv4 and would almost certainly have had a direct mapping from the public IPv4 addresses to a (tiny) subset of the IPv6 addresses. If that had been the case then IPv6 would have been in widespread use years ago.