alt Hacker NewsMobile carriers usually have stateful firewalls for IPv6 as well (otherwise you can get a lot of random noise on the air interface, draining both your battery and data plan), so it's an issue just the same.
The constrained resource there is only firewall-side memory, though, as opposed to that plus (IP, port) tuples for CG-NAT.
> otherwise you can get a lot of random noise on the air interface, draining both your battery and data plan
I highly doubt you get "random" data over ipv6. There are more ipv6 addresses than there are atoms on the planet.