^You are still looking at it too broadly... the Wii is already on a second peak by any standards that you seem to be counting at peaks... (ie dropping slightly before rising again) This Christmas it did better than last Christmas after all.
Personally I think the middle of 2009 (March to September) the Wii was just in decline from a poor software lineup. It had ridden on the back of Mario Kart Wii/Wii Fit and Smash Bros from early 2008 to early 2009, but with nothing significant in late 2008/early 2009 it started fading. The price cut, with help from Wii Sports Resort, Wii Fit Plus, and even bigger help from NSMBWii has stopped that lull.
If you look at the PS3 sales, from the price cut in November 2007 to November 2008 it would have sold more than it did from November 2008 to November 2009 if it wasn't for the PS3 slim.
Essay Pro