INTERNET ----- ASA ---- LAN
That is what we have today. the outside interface has got a public IP e.g. 80.1.1.1, the inside interface has a private IP and is the default gateway for my LAN (e.g. 10.10.10.1).
And of course there is NAT.
How is it going to work with ipv6? There is no NAT, I will get a block of ipv6 addresses from my ISP... and then? :)