IPv6 does not solve the need to renumber if you change providers (and no,
not everyone can be a provider -- IPv6 uses CIDR, just like IPv4). Until
that issue is addressed, there will be NATs. Even for v6.
I don't think so - first, because IPv6 has more hooks for renumbering
than v4 (though more work is needed); and second, because a lot of folks
will want to use IPv6 precisely because they need to avoid NAT breakage.
I'm not saying that there won't be any v6 NATs in the world (though we
should solidly and firmly declare them to be a protocol violation),
but they should be few and far between.
Keith