When i read the title, I first thought to myself that those 2 billion dollars will be pretty much worthless once everyone uses ipv6. But as soon as more ipv6 adresses are used (or CG-NAT), ipv4 adresses will become cheaper, so there seems to be a natural balance which will keep the state of "There are IPv4 adresses left" and "IPv4 adresses will run out sometime soon"