Valve tell us Steam now has over 30 million accounts, with new user growth up 178% over last year, and sales up over 200%. For reference, Xbox Live has 25 million accounts total. Even if Steam accounted for the entirety of PC gaming, which it doesn't by any means, this would give you some idea of how not dead it is.
Steam itself has now seen sales more than double every year for six years straight, and this year they more than tripled. Valve say they're gearing up the network to run at 400 "Gps". Presumably gigabytes per second, which makes their claim that it's "enough bandwidth to ship a digitized version of the Oxford English Dictionary 92.6 times per second" sightly confusing. Is the OED 4 gigs? Someone should zip that thing. Anyway, Steam is apparently fast and popular and PC gaming is massive and exploding and awesome. Here's a press release .