[alexhaefner]

They also see that their product is an app store, and it is going to get eaten up in the next few years as desktop and mobile OSes converge around security models that will not let unsigned apps from outside the app store onto user devices. This is the same reason they are building out their platform on linux. It may be the largest change they will have to make as a company, to try and convert their entire business away from it's traditional roots as an app (game) store for windows, as windows 8 and further generations introduce tighter security and stricter requirements around app distribution.

The same goes for mac. I'm sure they realized the mac app store was going to kill their business on mac. In a few OS generations, unsigned apps will be unallowed except for the most power users.

[morisy]

This was my initial thought, too. They're in a real pickle though: Is their long-term strategy really to build a platform/ecosystem to compete with Apple, Microsoft, Amazon AND Google? Because that's quite a crowded field, but if they don't build that ecosystem, Steam as a separate line of business for Valve seems like it would have its days numbered.

Only way I can see them getting around that and competing succesfully is if they offer a console-like appliance, which still seems like a huge departure and risk.