Some will argue that the Wii is making the pie bigger and that in the long run some of the new consumers will branch out and also purchase things other than uber casual titles.
Others say it's more likely Microsoft and Sony will adapt Nintendo's low cost, low quality, super casual approach and those who like games to have effort put into them and appeal to more than just kids (say, the average GAFer) will be left with less to look forward too and the insudtry as a whole will become completely casual.
Who's right? Who really knows, time will tell. But honestly, the most likely and probable otucome is going to be the latter, companies are motivated first and foremost by profit afterall, and if they can accomplish that without having to invest in quality it's all the better.
Wii = the next gen sweatshop