Bob Hinden writes:
2) For now, IANA should limit its allocation of IPv6 unicast
address space to the range of addresses that start with binary
value 001. The rest of the global unicast address space
(approximately 85% of the IPv6 address space) is reserved for future
definition and use, and is not to be assigned by IANA at this time.
It was well understood that it was important to keep most of the IPv6
address space open to allow for future use.
If it were well understood, nobody would have ever been foolish enough
to suggest blowing 2^125 addresses right up front. I've already
explained the folly of this in a previous post.