Microsoft? And PC gaming? Oh the irony.
Steam has already won here, and even the Mac App Store has leads over GFWL.
It is VERY clear that Microsoft is moving the traditional gamer community to its more managed (and profitable) Xbox ecosystem, while using PC as a haven for casual gaming. And for its PC IPs, it is also dumbing down the experience for them (Flight Simulator -> MS Flight, and ESPECIALLY the casual Civ V-esque Age of Empires Online, which annoys me as someone who grew up with Age II).
Even with these manoeuvres, it seems that MSFT is using its usual Ballmer-era business strategy of "copy first, try to profit second, innovate much later", which was successful for the Xbox but not for Zune, Windows Mobile, Kin, and (arguably) Windows Live.
If MSFT didn't have DirectX and Windows' absurdly high market share, I'd bet many PC-centric companies (Valve, id, Blizzard, most indie/doujin/smaller studios) would move elsewhere. Sadly, this is not the case (Carmack, one of the biggest OpenGL supporters, has changed mind and favours DirectX for development now).