"Once their stock started to dwindle, a lot of carriers went, 'Wow, we'd better get what address space we can, quickly,'" Liu said. The Asian registry depleted its last block in mid-April. Such a run on addresses in Europe is "a real possibility" in 2012, he said. RIPE and other registries have already tightened the rules for IPv4 address allocation to prevent hoarding and panic from draining the pool too quickly, but RIPE might yet do more, he said.
In 2013, it will be North America's turn to watch its Internet registry run out of IPv4 addresses, according to Huston's forecast. Africa and Latin America will face the same in 2014.
Adoption is still sparse
But despite the impending depletion of addresses, most enterprises didn't begin upgrading to IPv6 last year. As of October, fewer than 1 percent of all subdomains under the .com, .net and .org top-level domains had IPv6-enabled Web servers on them, according to an automated sampling commissioned by Infoblox. Notably, that survey excluded .gov and individual country domains, where use could be higher.
Most enterprises outside Asia are not acting aggressively to upgrade, and most won't next year either, according to IDC analyst Nav Chander.
"Most of them understand that they can live without having to make any major investments immediately," Chander said.
And most carriers, though they have upgraded their own infrastructures to handle IPv6 and are offering consulting services, aren't strongly pushing customers to move to the new protocol, Chander said.
The lack of IPv4 addresses probably won't force many enterprises or carriers into IPv6 in the next few years, observers said. Most organizations that adopt IPv6 will do so with dual-stack configurations that support both protocols, and NAT (network address translation) can bridge the gap to make IPv4 resources available to IPv6-only systems and vice versa, Liu of Infoblox said.
Eventually, using NAT for every connection between new and old systems could slow down the Internet experience, but the traffic going through those systems won't be heavy enough to cause problems in 2012, Liu predicted.
BYOD isn't a threat yet
Letting employees use their own mobile phones and tablets at work won't force companies to use IPv6, either, he said. As long as the IT department has done a good job of laying out its private, internal address space, which can continue using IPv4 addresses indefinitely, there should be enough for the consumer devices, Liu said.
However, other trends that are expected to grow next year could help to drive adoption of IPv6.