It is inevitable that this gen will sell less than last gens 270 Million + systems. The market has changed dramatically just in the last 3 years. Tablets and smartphones have consumed a majority of the casual buyers (about 50 million+ Wii units last gen). That alone will lead to a dramatic shift. Also, the 360 probably picked up 10-20 million casuals with the Kinect gimmick. I am not saying that all casuals will abandon the console market, I am just saying that there will be fewer. Even a bunch of the core gamers have converted to steam because of the length of this console generation. Some or many may just stick with PC's with a smartphone or tablet. Within 2 years, tablet power will be enough to output games in 1080p(or even 720p) that are "good enough" for the casual crowds to no bother with a console.
Like I said, it's a different marketplace.
It is near the end of the end....