I always thought that when we ran out of IP4, that some of the companies holding on to Class A blocks would release parts of those for use. I'm not a master of how blocks are assigned or if addressing wise it would be feasible but really, does Ford fully use its Class A block? Prudential Insurance? Eli Lilly? GE?
They could be playing the long view and realizing how much that address space is worth. If I were in charge of IT at those companies, I'd renumber out of the block and start thinking about selling the space, once it gets tight.
I've noticed that the perceived view in the netops community -- backed up by mailing list messages today, even -- is that such an IPv4 broker market is an inevitability no matter what the RIRs do. There are policies about it, but some regions (i.e., APNIC) have a model that encourages reselling space without their involvement.
Many people don't realize how non-trivial renumbering a network is. I transitioned the resnet at a public university from a /19 to a new /18, and it took several months of planning to pull off.
90% of the space was assigned via DHCP, but that remaining 10% which was statically assigned was a lot of work. Imagine tracking down every device assigned an IP address, scattered across a college campus.
Our routing configuration was trivial (single super-net, single site, &c), compacting an enterprise /8 would be an insane amount of work.
The long view isn't making a quick buck off v4, it's moving to v6 as quickly as possible.
Random point about this (my current employer is a national lab):
In 2006, the OMB issued a requirement that new DoD/DoE/USG/etc IT spend ("to the maximum extent practicable") be IPv6-capable, and tasked NIST with developing a testing framework for determining compliance:
Basically, we have to be IPv6-capable on external services by 2012, and be ready for it enterprise-wide (for anything that touches the Internet; offline farms, etc. are exempt) by 2014. I don't suspect many organizations are going to hit that, but that's the target, and we're taking it pretty seriously here.
Also, here's a random resource: a totally unofficial IPv6 survey:
