First, the world continues to turn on its axis (for instance, it is not the case that I am suddenly unable to procure a cheap Slicehost instance with a routable /32). But now there's one less hypoxic argument about the impending death of the Internet if we don't immediately cut over to IPv6.
Second, plenty of companies are holding on to /16s, or multiple /16s, or (contiguously routable) /15s, or (god help us this is apparently true) /8s. Those addresses will urgently begin to pick up a real market value. Fantastic: IPv4 addresses always should have had a monetary value commensurate with their market value, and now some of those vanity allocations will get liquidated.
there are lots of companies with /8's that can't possibly be using all of the addresses. ibm has 9/8, xerox has 13/8, hp has 15/8 and 16/8, apple has 17/8, mit has 18/8, ford has 19/8, csc.com has 20/8, etc.
Regardless of whether or not they are using all of the addresses, they probably find it easier to continue holding onto them for future needs and convenience than to give any of them up for short term gain.
IT Departments hate having to manage these sorts of changes. Imagine all of the firewall rules that might have to be updated if suddenly part of a /8 range was to be considered "external".
i think arin/iana will have to start doing audits and make these companies justify their continued use of their entire /8s or else have to give parts of them back. ip addresses aren't owned, they're just leased from arin and companies have to pay yearly fees of thousands of dollars to keep using them.
arin has gotten pretty strict on giving out additional space to ISPs asking for further allocations due to the pool shortage. once the pool runs dry, the only thing they'll be able to do is break up previous allocations into smaller ones.
these companies with /8s only have them because they were given out in the mid '80s, not because they've ever shown a need for 16 million host addresses.
ip addresses aren't owned, they're just leased from arin and companies have to pay yearly fees of thousands of dollars to keep using them.
The legacy blocks were never owned by ARIN. It is unclear whether they have any right to claim anything over them. IANA may have rights to claim ownership, ARIN definitely does not. ARIN is merely one of five RIRs that ask for addresses from IANA.
Where do you end up, when can you get there, and will the results be worth it?
With major businesses that have their networks disrupted (Halliburton, HP, GE, IBM, Apple, etc), with the router and firewall and server and client and NAT reconfigurations, and a whole pile of administrative repercussions and squabbles from any revocation certain, where the sections of the blocks won't be available until after the businesses are able to clear the subnets, and how long will those recovered IP addresses delay the inevitable?
Wave a magic wand and recall, say, five US DoD /8 blocks back. (Something which will not happen, but we will assume for the moment that US DoD is on the front edge of IPv6 adoption.) How long will those five /8 blocks delay the exhaustion?
And how much of that consolidation effort will detract from rolling out IPv6 and 6to4 tunnels and NAT64 deployment?
Is the cost of all that effort and disruption worth it?
True, but that doesn't necessarily mean that there are large, unoccupied routeable blocks within their allocated ranges that those organizations could easily hand back. More likely, they've got some sparse set of addresses scattered all over the place, reflecting allocations to their subdivisions.
Hey, it's 1992; why not give that research group a /16 if you've got the bits? There's no immediate need, but they might use some fraction of it eventually. And they parcel out /8s to subgroups, a few at a time, averaging out to maybe a dozen machines (some groups with more, some with less). Upshot: in 2011, there's an internal /16 with a few hundred machines on it --- but reallocating it to a smaller CIDR block which reflects actual usage requires negotiations up and down the hierarchy. And this kind of cruft has been piling up all over the place for decades; sorting it out may be hard enough that some of 'em would rather fight than pull the switch.
First, the world continues to turn on its axis (for instance, it is not the case that I am suddenly unable to procure a cheap Slicehost instance with a routable /32). But now there's one less hypoxic argument about the impending death of the Internet if we don't immediately cut over to IPv6.
Second, plenty of companies are holding on to /16s, or multiple /16s, or (contiguously routable) /15s, or (god help us this is apparently true) /8s. Those addresses will urgently begin to pick up a real market value. Fantastic: IPv4 addresses always should have had a monetary value commensurate with their market value, and now some of those vanity allocations will get liquidated.