Now, if you have a site which has more hosts than it can get external IPv4
addresses for, then as long as there are considerable numbers of IPv4 hosts a
site needs to interoperate with, *deploying IPv6 internally to the site does
the site basically no good at all*. Why?
this sounds like a slight exaggeration, but I do think that the main
incentive to deploy v6 will come from the need to communicate with global
addresses to points *outside* of folks' internal networks.
it doesn't follow that deploying IPv6 internally to a site does no good
at all - it will of course do some good if the site has applications
on internal hosts that need to communicate with external hosts using
global addresses. and of course having v6 deployed internally would
allow the site to run those same applications interally without any
configuration changes.
but if you're trying to make the point that there's little purpose in
having your own IPv6 island - I think that's basically right.
Keith