They're capable of being used for gaming, That's the point, the potential market is huge and as you've been told repeatedly, the PC games market is about far more than just the one narrow segment of retail copies of high budget games. Within that market, there are going to be people with X1900's still playing the latest releases at low detail, people with GTX 460's who just play casual games and every cominbation you can think of in between. There's massive scope for tapping and exploiting that market and its myriad niches, and high-handedly 'excluding the people playing browser games or social network stuff' would be sheer stupidity on the side of developers and publishers.
Also, why is 322 million by 2013 stupid? There are over 70 million graphics cards sold every year, they're not being bought by businesses. The new Intel chips will have integrated graphics more than powerful enough to run 3D games at 720p. Seems a reasonable estimate to me.
