I think Wii and 360 peaked in 2008. I think MS was hoping for a bigger year in 2009 than they are going to get, with 360 just sneaking into the red in the final run to the end of the year. I doubt Natal at the end of 2010 will make such a massive difference that it will overcome 360's reduced sales through the first 3 quarters of 2010. At least not without a price cut at the same time. If Natal releases in a bundle with the same price as the units are now sales might increase a bit, but not amazingly so.
The Wii price cut was surprisingly more effective than I thought, though so far it hasn't brought its sales up to 2008 levels. BF week and NSMB Wii Japan week might see a change in fortunes. 2010 can easily be better than 2009 for Wii. But with a resurgent PS3 I don't see Wii performing as well as it did in 2008.
Unless there is another price cut in the offing, in 2010 PS3 is likely to be like 360 was in 2009: building a strong lead through much of 2010, only to see it wiped out some time after it runs up against 2009's Slim release week. Wand won't do much for PS3 sales, but I do hope there is good bundling, decent uptake by the current install base, all supported by good software. Having said that if GT5, GoW III and FFXIII (Western release) all give decent and reasonably sustained HW boosts in their favoured markets then the lead PS3 builds up might just overcome the late 2009 surge.
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
"When the power of love overcomes the love of power, the world will know peace."
Jimi Hendrix