I have a theory. I was thinking what would be the most likely reason behind if the Nintendo Wii came in 3rd place in sales. I came to a conclusion that it would more than likely be the graphics. When the average person goes video game shopping, or parent goes shopping for their kid for christmas, when they are looking at what games to buy, what do most of them look at? What they see in the screenshots of the game on the box. If a person goes out to buy an unspecified game, and they look at the visuals compared to the PS3, they are naturally going to be inclined to go the sony route.
So my theory is that for the next Nintendo, they are finally going to up the visuals so that they can compete with Sony, Microsoft, or any other gaming hardware company at the time in all aspects of the system, including high-end graphics. If they did do that, obviously the nintendo with be more expensive, but they would still try and be economical and only raise it by like $50 more than the Wii will be.