Nah, the consoles will definately last a good deal longer than three years. I'm thinking atleast 5, with MS again getting the jump, or possibly nintendo, bringing forth the same controller with an update piece of hardware to go with it.
Look at company predictions and you will definately see what i'm talking about. Sony is looking to make profits in the long run, not the short run, and the short run is definately the first two years.