The Rising Cost of IPv4
IPv6 only network less expensive to operate.
Although many organizations run both IPv6 and IPv4 the decommissioning of IPv4 networks is a long way off. According to experts in this Network World story, the rising cost of operating an IPv4 network has businesses looking at IPv6 as a more attractive solution. Network World also reports that the effort put into operating networks with IPv4 may distract from putting effort into making progress toward IPv6.
"Do you have a static IP address at the perimeter of your broadband Internet connection today? How much a month do you pay for that static public IPv4 address? Some people have paid as little as $5/month for a static IP but this is like to increase to $20/month, $40/month and $50/month. I have also heard about service providers that charge an extra $100/month for a static IPv4 address. The monthly rental of a public IP address is likely to increase or even go away as carriers are forced to move to CGN/LSN/NAT444. Furthermore, with the introduction of CGN/LSN, you will not be able to run a server at your location. Because you won't have a static public address your ability to have a single DNS or Dynamic-DNS service is impossible.