For core links it should IMHO be mostly possible to keep them IPv4/IPv6 dual-stack.
What's wrong with MPLS in the core and 6PE at the edge? Right there you have two possible tactics that are worthy of being publicly discussed and compared.
Towards endusers it can become nasty, eg it would require upgrades of the CPE and also the infrastructure might need to be upgraded.
On the other hand, there are vendors like Hexago that sell gateways which can simplify this. Perhaps Hexago and other vendors should be invited to showcase their boxes at a NANOG meeting. The great power of NANOG has always been that the operations, research and vendor community meet together and share information. Vendors go away and build better boxes/software, researchers go away and follow new avenues of investigation, operators go away and change their processes and network designs. Back in the day, there was something called Interop where vendors were put under the thumb. Since there is no such thing for IPv6, perhaps NANOG could step into that vacuum.
For Cable systems only recently the Docsis 3.0 standard was released and that would still require a lot of upgrades. Tunneling those users might be a way to provide IPv6 connectivity to these users without much ado.
Cable is a consumer access technology. Realistically, IPv6 is going to kick off with deployments to research, education and business users, not consumers. Cable will catch up in their own good time as they are driven to IPv6 by RFC 1918 exhaustion. --Michael Dillon