Currently the economics are simple. After the runout of ipv4 if you want your network to grow you must deploy ipv6, and carrier grade NAT. It is the networks that are expanding and changing that have to pay the cost. Once there is a real ipv6 presence Verizon LTE, Comcast, T-mobile, etc the rest of the issues will be worked out. This is something that we need to move forward with, but I totally fail to see how is something that must happen for everyone in 200 days, NAT gives IPv4 enough life to implement dual stack during the transition.
Furthermore it has been shown that if you plan ahead and get ipv6 into your normal equipment purchasing cycle it is not a significant cost. So I guess we will see who didn't plan ahead and how it bites them.