With modern LAN-less application publishing strategies (this includes web apps, remote desktop technologies and others) end user devices are effectively thin clients. These devices often provide no more processing capacity than is necessary to display the application. They are a window into the infrastructure, not a gateway. They look at the servers – they aren't sitting inside the castle with them.
Thinking of end user devices as view panels or windows rather than computing devices is the key to making BYOD an advantage to the IT department rather than its bane.
Of course, this plays into the usual ebb and flow of fat and thin clients over the history of computing. The tide will change again, but for now, this is our current opportunity. End users want the illusion of control and the reality of picking the device that is best suited to their needs – which are almost strictly physical needs whether of fashion or function.
IT departments want the reality of control and should be happy to allow end users to pick their own devices. Everyone can win.
The key, of course, is eliminating legacy applications or finding workarounds. Technological approaches such as VDI, terminal servers or even racks of datacenter-housed desktops potentially provide fallback strategies. These resources can be accessed from nearly any device. Simultaneously, "view" layer technologies like HTML 5 look to provide elegant, modern options for exposing applications, shifting display-related processing to the end user device and standardizing on a protocol that is likely to exist ubiquitously in the very near future. The technologies are there today.
With the corporate network shrunk down to being only the infrastructure servers and associated networking gear, suddenly IT departments have the potential for greater control and more flexibility while giving up little. End users are happy, IT is happy.
BYOD is an opportunity for IT to exert greater control, tighter security all while giving the impression of being approachable and flexible.