There is still plenty of IPv4 space available, it's just very badly distributed, for instance, due to early limits in Cisco's IOS, Chevron acquired an insane 26 Class B address blocks when connecting to the net back in the early 90s! With CIDR, we can easily reuse the many unused addrs like those, but the pain of readdressing has their owners sitting on them, raising prices and making them even more reluctant to turn loose of any for fear they won't be able to get them back...

And, let's face it, IPv6 addressing is so fundamentally horked-up that it's practically only usable by propellerheads in the cloud backend: First, the addresses are too damn long and unwieldy to really be used; and second, even most people reading this, tech people in a tech forum, struggle to really grasp the inane IPv6 address shortening rules! Like X.400 mail addresses, they work technically, but are unusable in practice.

(For those of you fortunate enough not to remember, the best way to get and transfer someone's X.400 address, even within the X.400 network, was to have them mail someone through an internet gateway and use whatever it said. Marshall Rose devoted an entire chapter to ranting about this in his Internet Mail book...)