[bb88]

You're still going to have a firewall, it just won't be NAT based.

[Dagger2]

NAT isn't even a firewall in the first place. The firewall you need for v6? You've already got it in v4, if you've secured your v4 network.

...which a lot of people haven't, because they falsely believe that NAT by itself is enough to stop all inbound connections to their network.