Games for Windows live has to be the biggest failure Microsoft has every made. So I go to the gfw live marketplace after downloading a patch to see a big add for operation anchorage. Buy the game and you have to install Games for Windows Live and Steam.
However, with a few tweaks, Microsoft can not only make Windows 10 a great place to play games, but could also bring Windows and Xbox.
If recent Microsoft-published games like Halo Wars and Voodoo Vince getting released on Steam indicate a trend, maybe the Windows Store's.