Major Nelson has given us some straight fact when it comes to console lifecycles. On his blog he wrote:

"Today we announced that by extending the capabilities of the Xbox platform with Kinect and Xbox LIVE, Microsoft has “changed the tail” of the typical console lifecycle, showing dramatic gains in the fifth and sixth years of this generation"

This means that current generation console will see many more years of relevenacy than consoles before them. Major Nelson went on to point out some specifics regarding the Xbox 360.

Microsoft has now sold 55 million Xbox 360 consoles across 38 countries and sales are accelerating.
Xbox 360 maintains its lead in the U.S. as the top selling console in 2011, and ten of the past eleven months.
In the first four months of 2011, Xbox 360 has seen a 29 percent year over year increase in sales, which is more than triple the growth of PlayStation 3 and the largest growth of any console on the market.
There are now nearly 35 million active Xbox LIVE members worldwide spending an average of almost 60 hours a month on the service.
Cumulatively Xbox LIVE members are now logging 2.1 billion entertainment hours a month.

GGCwalk via gamergaia.com »