^It's the video game industry. Just like the sign industry or car industry, there will only be a certain amount of money spent each year in the given industry. When they speak of an industry as being a $4 billion industry, that's the total which will be split up amongst all competitors in said industry.
The CONSOLES are not in competition, but the COMPANIES surely are. There is a "pie" and each company wants as big a piece as possible. Nintendo was smart, and decided that instead of going after only the preexisting "pie," they would also go after money that wasn't previously available (Blue Ocean).
My End of 2008 Hardware Predictions (console only):
Wii : 50 million
360: 28 million
PS3: 24 million
These predictions were made on January 3rd and won't be revised
