IPv6 has been in development since
1996.
The problem is it is completely incompatible with IPv4, much the same way 64bit windows is incompatible with 32-bit drivers. OK, so not the exact same, but you get my point.
So why can I run 32-bit apps in 64-bit windows? Because
WOW (Windows on Windows) encapsulates the program in a 64-bit emulator for efficient machine language translation from 32-bit to 64-bit. However, this means that any 1 32-bit program on Windows x64 cannot use more than 3GB of ram (much like how the 32-bit IPv4 cannot be more than 4 Billion addresses).
Anyway, so the internet is tricky, and we have been using IPv6 for YEARS. You just aren't aware of it, nor care. Most point-to-point transmissions (think ISP to ISP) are encapsulating IPv4 packets into IPv6 packets. Thus the problem is not as terrible as you think.
The big problem is that there is very limited activation of door-to-door IPv6 transport going on, even though anyone with a computer made after 2000 has the capability to do it. So that's where national IPv6 day comes in... to weed out the bastards who are not updating their computers...
