Verizon, why wait ten years?

Verizon Wireless recently announced that they estimate to keep their CDMA 3G network alive for another ten years before shutting it down. At the same time they expect to have full LTE 4G coverage by the end of next year.

Why wait another ten years to shut down a network which is based on an already largely obsolete technology?

I understand that there is a need for time to migrate customers to the 4G network, as well as time to better understand how routing voice calls over 4G networks will work when VoLTE is implemented. There will also have to be built in time for the introduction of lower-priced 4G handsets to enter the market so that Verizon can offer a full range of 4G handsets.

But ten years!? Ten years is an eternity when it comes to the wireless space. The first iPhone was launched in 2007 and that feels like a long time ago today.

My bet is that the Verizon 3G network will be largely gone in five years or less, with most of its spectrum reallocated to the 4G network.