The IANA (Internet Assigned Number Authority) distributes IPv6 address to RIR’s (Regional Internet Registry’s) around the world. At the moment there are five RIR’s and each of them is responsible for allocating IPv6 address space to ISP’s (Internet Service Providers) and, in some cases, End-User organizations. Once a block of addresses is allocated to an ISP it becomes their responsibility to distribute the address space to their customer base.
“You hear that? That is the sound of inevitability…” – Agent Smith, The Matrix.
You will migrate to IPv6. It is happening. You will not be able to resist. The IANA gave out the last IPv4 allocations on 2/1/2011. There are no more. As I write, the RIR’s will completely run out of IPv4 addresses within days. Not years, not months …days.