The following comes from a a DFC Intelligence report...
For its generation, the Xbox 360, not the Wii, will end up as the number one selling console system in the U.S. Shockingly it was in the later years of its life that the Xbox 360 really took off.
Much has been made about a steady video game sales decline in the past three years. In reality the decline has mainly been due to the aging console systems and more importantly because of Nintendo’s collapse. Unlike Microsoft, Nintendo has been in a major downward cycle, much of it self-inflicted. Nintendo’s spin for the Wii U focused on how it made more revenue than the Wii at launch. Of course, the Wii was supply constrained at launch and sold at a lower price so that is not surprising. The reality is that many Wii U systems were sitting unsold on shelves at year end. Consumers love games more than ever but a new order of game providers is resulting in market shifts that are proving painful for Nintendo and other established game companies.
There's no denying that the Wii took a hard fall in its later years. Unfortunately, that seems to be the trend with Nintendo consoles in recent memory. It happened with the N64, Cube and now Wii. Will Nintendo really be able to buck that trend with Wii U?