There is not much substantiated information that would put the Xbox into the definite space of delay, but some bits published by SemiAccurate, suggest that Microsoft is currently dealing with the usual pre-production annoyances and is scrambling to get the processor of the console into reliable manufacturing.
SemiAccurate's Charlie Demerjian believes that a finalized chip will have to be put into production by November 1 in order to be able to qualify it for mass production this year. In order to secure the rumored September 2013 launch date, Microsoft and its partners will have to figure out their yield problems by February 2013 to be able to finalize the console.
It may be a bit early to assess any yield issues and how they will affect the release of the console. However, we are not so sure about the September launch date. Our sources at game developers point to an October 2013 target. September is awfully close to the back-to-school season and implies limited consumer funds. Microsoft has been historically targeting October or November as the best months of the year to launch its cornerstone products and that is unlikely to change with the next Xbox.
The original Xbox was launched in November 2001, and the Xbox 360 in November 2005. If we look at the past Windows releases, Windows XP came in October 2001, Windows Vista in January 2007 (which was an accident and a delay from the planned October 2006 launch date, when Microsoft was certain that it would miss the Christmas season), Windows 7 was launched in October 2009 and Windows 8 will launch in October 2012. Microsoft rarely changes its product introduction strategy and there is no indication or reason why the company would change it with the Xbox 720. If it is released in 2013, it will most likely launch in November to capture as much Christmas revenue as it can.