[milankragujevic]

UPnP is completely useless for CGNAT, and PCP would work only IF the CGNAT gateway would support it, which most don't (or it's disabled).

I don't think great difficulty about NAT is concerning CPE NAT, i.e. your local network, as it's trivial to forward ports (or port ranges) manually. Most problems are with CGNAT, i.e. on mobile broadband or some cable and DSL providers.

[bzb5]

Where I am there are more isps that support pcp than isps that support ipv6 at all (zero)

[milankragujevic]

Where I am the number of ISPs that support PCP is the same as the number of ISPs that support IPv6 - zero.

My point wasn't that IPv6 is currently the answer, my point was that it's impossible to host anything or be reachable by anyone for A LOT of people in the world.

[xxpor]

Using CGNAT while not offering IPv6 at all is professional malpractice.