[forty]

It's all about incentive I guess. What do they win by supporting ipv6?

From the service provider point of view, as long as their customers can reach them with ipv4, they have no reasons to switch.

From the customer ISP point of view, as long as services people use provide an ipv4 option, there is no reasons to switch.

Maybe the ones that have the most reasons to switch are new internet services and new ISP which might have a hard time getting ipv4 blocks. But that's just one more reason for established services not to move too fast :/

[eppp]

Not only do you have to support ipv6, ipv4 will never go away on any meaningful timescale. So even if you do the right thing and deploy it you still have the same ipv4 address constraints. There is no winning.