"It would imply that 25% of the projected life of IPv6 is 42 years, meaning that even under this flawed plan it would have a life of ~126 years?"
I have no idea where those numbers come from. IPv6 allows for about 35 trillion networks with a /48 prefix under the space so far allocated to the registries, which is only 1/8 of the theoretical total space. The address space lifetime isn't even worth calculating. IPv6 may have a lifetime, but without idiocies like this ITU proposal, it isn't limited by address exhaustion.