Another article by Patrick Moorhead piqued my interest today. It asks a question about whether network complexity is better solved by virtualization, or a change in hardware. Obviously, a lot of vendors will push their hardware as the best way to achieve software-defined networking, as opposed to the more free and open virtualization strategies involving standards like OpenFlow. But I think this in-depth paper, and Moorhead's opinions both point toward network virtualization, unless you already have a variety of specialized hardware.
The article also has a neat diagram of commodity rack servers, blades, and hyperscale servers.