A popular video game blog recently reported that the next generation Xbox and PlayStation consoles will not be available before 2014. Microsoft and Sony are apparently trying to milk the current generation, despite an already extended console life-cycle and the fact that Nintendo will be launching its next machine by the end of 2012.
It's possible that either company could launch as early as 2013 if they feel pushed, though. A new Xbox in 2013 would likely only be a Kinect-upgraded 360 rather then a true next-gen console, which would still be held back until 2014. Microsoft has reportedly not even decided which components will be a part of the next-gen Xbox yet. The company's board is still debating over strategy, trying to decide whether to go for profit on day one with the new device or take a longer term approach and launch at a loss, which is what both Microsoft and Sony usually do.