I think the key thing to consider is the fairly lackluster year for Nintendo software vs a major technology add-on for Microsoft. I can honestly say that there may be only 2-3 games that came out this year for the Wii that appealed to me at all, whereas the 360 had several good games released this year PLUS Kinect.
What will be the key thing for 2011 is how well Kinect continues to sell/increase userbase vs Nintendo's Wii releases for 2011. Factoring a new Zelda game is a major difference, as it pretty much shakes up the ant farm and gets more people to buy Nintendo consoles. Whereas Twillight Princess gave the option for some GameCube holdouts, Zelda fans will HAVE to play this one on the Wii. Should prove an interesting battle.
According to the chart in the OP, it's also interesting to note that the PS3 remains unchanged YoY, which is both good and bad. Good because it's not losing sales, but bad because its not gaining on either of the other systems - in the Americas of course. We know the Japanese circuit is different.
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