There is also an aspect of this transition I don't think we've seen before (in networking). A large percentage of end users are on technologies (cable modem, dsl, even dial up) who's configuration is entirely driven out of a provisioning database.
Once the backbone is rolled out, the nameservers, dhcp, and configuration servers dual-stacked many ISP's could enable IPv6 for all of their customers overnight with only a few keystrokes.
*If* the whole IPv6 config can be driven from the same database. For the time being, DHCPv6 cannot deliver a default gateway to customers (and there is a religious faction within the IPv6 community which seem to want to prevent this at all costs). As long as we have the dependency on RA for default gateways, what you suggest is considerably more difficult. Steinar Haug, Nethelp consulting, sthaug@nethelp.no