This is going to become a problem.

IPv4 is very old, and has a limit of ip's that don't suffice for today needs.
Implementing ipv6 is hard, but backward compatibility can be even more hard.

NAT on the ISP is a crappy solution to this, but has the obvious problem: You are not on the internet, your computer is on a lan; Another problem: You can't open ports. It will make reaching server from other lans very hard or imposible. Probably this problem can be solved for things like Skype or consoles. Can use something like hamachi (a big Virtual LAN) builtin in the console. But us, PC gamers are going to get fucked over.

What we have to do?

Avoid ISP's that use this tecnique, and don't fuly implement IPv6.
Opt-out of any NAT.