Amazon is one of those companies that does what they say. They recently completed their examination of SDN technologies and made their deployment decision moving away from vertically integrated, expensive systems in favor of standards-based systems and software.
While vendors and the academia have been pushing SDN aggressively, network operators have been cautious in transforming their networks toward less vertically integrated solutions. This is understandable, networking hardware and the software systems that control them, are a complex and proprietary discipline that only a few, specially trained individuals can truly understand and deploy.
That used to be true in the data center, but not any longer. Today, businesses can buy server hardware from any vendor, virtualize it with any hypervisor and then run any application on it with full control and visibility as well as upgrade various components at any time. The benefit is maximum control and flexibility across a low-cost infrastructure.