tkjinak has a point. Indeed, a big part of Sony's success over the past several years has been opening up markets in Europe and elsewhere in the world. The "Others" category certainly has far more population than North America and Japan combined, but:
A) most of the population in these countries is not very wealthy, and
B) the industry has always focused more on the North American and Japanese market
The Japanese market isn't shrinking on the handheld side. On the home console side...maybe. I think it is going to depend on Nintendo's ability to bring some more disruptive games to Wii. DS wasn't built on Brain Training alone.