IPv6 will fundamentally revolutionise networking. I cant be bothered to explain NAT and RFC1918 but there will no longer be requirement for private networks. Never before has the firewall and IDS been more important.
The IPv6 address space delivers 340,282,366,920,938,463,463,374,607,431,768,211,456 addresses as opposed to 4,294,967,296 which is why we havent enough now and we must use things like NAT to preserve address space.
Mind boggling. Arguably, less so than NAT is now, but when you've got your head round that then this is a paradigm shift.