Ail the Wii software market is 193m in the Americas vs 34m in Japan. That is what is preventing a western slowdown. The entire NES/DS market for the Americas was 230m/205m. Wii is going to obliterate those figures for software and that will continue to ensure that games which take advantage of the western software base will continue to be developed. The problem is games aimed at western audiences rarely perform well in Japan, even when made by Japanese developers, so the Wii software situation in Japan is likely to remain dire, at least until Monster Hunter 3 and Dragon Quest X begin rounding it out as a third party hit machine in the way the big hits from Activision, EA, Sega, Ubisoft and Capcom have helped Wii in the west.

The hardware ratio is 23,000,000 to 8,000,000 in the Americas to Japan despite the slowdown in Japan recently. If Wii in Japan had PS2 like support among Japanese developers the Americas to Japan SW ratio would be only 2.5 to 3.5 times greater than in the west, instead of ~six times larger.

There are at least 10 more million selling Wii games (Mario & Sonic, Wii Sports Resort, EA Active, Punch Out, Guitar Hero V, DJ Hero, Beatles: Rockband, Red Steel 2, the Rayman comedy adventure, Tiger Woods, Wii Fit Plus if it exists) in the west this year, Japan has at most 3 (Wii Fit + if it exists?, Wii Sports Resort, Monster Hunter 3).

Game purchases per user are a measure of satisfaction though.

The Wii rate in the Americas is 8+. Its half that in Japan.

My point is you can infer the future of hardware sales from software sales. You can buy yourself a good quarter or two if you string together enough hits to keep your game purchases per user rate high. Wii hasn't had a quarter like that in Japan for a while now, but in the west there is more hit software to prevent a rise in disinterest from happening quickly.