Telenet in Belgium has a complete IPv6 dualstack rollout on DOCSIS, so it's definitely possible. They've had it for quite some time now, and they're the reason

Telenet in Belgium has a complete IPv6 dualstack rollout on DOCSIS, so it's definitely possible. They've had it for quite some time now, and they're the reason why Belgium is near 50% Google traffic over IPv6. It really just takes some planning and some guts to make the switch. If done right everyone benefits. (Have to add that Telenet has the advantage that they have full control of every customer's modem, which usually includes the home network router / gateway, which does simplify a good rollout.)