After Asia and Europe, North America is next in line to run out of IP addresses.

[kyrathaba]

http://arstechnica.com/business/2013/04/inet-denver-considers-internet-life-without-ipv4-addresses/

According to Huston, at some point during the next five years we have to make a choice. We can go down the path of Carrier Grade NATs (CGNs) and put an entire neighborhood behind a single shared IPv4 address. Or, we can bite the bullet and upgrade or replace all those devices (mostly in the last mile infrastructure) that are keeping us from moving towards IPv6. "And it's not yet clear which path the Internet will take!"

[Stoic Joker]

Oh goody, no more of those pesky NAT firewalls seperation public and private systems. With IPv6 everything is exposed as a public interface.

Yes, I'm being sarcastic...(having been stuck studying IPv6 a great deal lately)...but it's also quite true(ly a hackers wet dream).

[SeraphimLabs]

Yeah. I honestly want to keep NAT in IPv6 purely from a security and privacy standpoint.

Without it you have to get into a rather complex traffic shaping firewall configuration, that will in all probability be full of holes.

But carrier grade NATs just mean one more way that ISPs will be able to control what we do.

Just, the corporate powers that be will do anything to boost their profits. And if carrier-grade NATs are cheaper than backend upgrades, you can bet that's what they'll do.