Part of this sales slump can be explained by economic conditions in Japan. I was reading an article in the economist regarding Japan's economist performance of late as I suspected the slump had more to do with economic factors than seasonal slumps.
It looks to me as if the slowdown for the Wii and DS occurred around the same time that the sup-prime mortages fiasco. Furthermore on September 10th government figures indicated that they economy had fallen by 1.2% over a one year period. With a recession a possibility, spending on luxury goods would have taken a hit, particularly as recessions are monetary in nature and typically involve individuals saving money as a safety net for when times get rough. When enough people do this it effectively becomes a self-fulfilling prophecy and a recession occurs.
I guess my point is that this slump could be more serious than it appears and games like SMG will do little to rectify things. If the Japanese economy has weakened than spending money on luxury items will no longer be important and I would expect Christmas sales to be somewhat depressed.
Of course hopefully all this is wrong, particularly as you never want to see a country in a recession or heading towards one. But I thought it made for an interesting and certainly a very different view of what we've been seeing in the sales data :)
