Depends on what kind of ISP they are. When they are already an ARIN member they can indeed, for the coming couple of years, get 'free' IPv6 address space. But getting address space is not everything; you also need to train people, have the helpdesk updated to support it, upgrade all your equipment, solve a lot of new problems and way way way more. Beg hard, worship several gods at once or: donate them a lot of money. The largest hurdle: Return on Investment For an ISP there currently still is no real reason to start moving to IPv6 except for having it done already instead of getting hit late and then having a big burden. As such any investment they make like training, equipment, upgrades, and a lot lot more isn't directly getting money flowing into their direction. Thus there is no business case for them now and thus why should they bother with it? That is exactly the step that SixXS can provide to them: What can SixXS do for an ISP? but they would still need to make available connectivity to the rest of the world and configure routers, upgrade their monitoring and lots more.

Just keep in mind that I expect the US to be relative slow in picking up IPv6. They have a larger number of IPv4 addresses assigned for historical reasons.

Just FYI, OCCAID is currently aggressively pursuing extensive IPv4 peering relationships with many ISPs in US that we can meet at exchange points. The goal of this project is to enhance the tunneled IPv6 path for many ISP end-users so that they can reach IPv6 SixXS US, etc tunnel POPs at a much faster speed with low latency. We will be joining additional exchange points for IPv4 peering, including Equinix Dallas/Chicago, so stay tuned for more improvements! James OCCAID