Re: Time to give up on IPv6?
Or, you know, don't waste money until you actually go live with IPv6 for a reason other than "because"?
Punching holes in NAT doesn't even require UPnP, any co-operative endpoints can do it through at least one layer at each end. This isn't new, and off the shelf libraries to do it exist. So yeah, if you write an app and refuse to include NAT traversal, it won't work well. That's not an IPv4 problem, that's a programmer problem.
BTW many VOIP systems work fine across NAT. Even then a simple port mapping would square them, unless they were deployed by an ISP/Carrier that refuses to allow other service ports and is running a raw connection. You still also have plenty of better options like VPN bridging, etc. to get traffic from point A to point B, and get actual security to boot.
Even outdated WRT class home firewalls used/use both NAT AND a stateful firewall, nobody was arguing that it was adequate by itself, just that they allowed configuring policy for both at the same time(except the harebrained ones that made you enter it twice, lookin at you sonicwall).
Their IPv6 polices often didn't do this, but that's just bad design, not a protocol issue. But a default rule of block all incoming traffic not associated with an established outbound connection does the same thing. That does lead me to wonder why it took 10 years to get that in a GUI for IPv6 on so many routers, home or business class though.