Steam

It is funny that people think Valve would sell out instead of becoming the big evil.

As Valve continues developing an OS agnostic platform, they start building into various tools that require a Steam account to play games in order to defend their app store. Maybe they buy Unity and make it a Steam exclusive, maybe they make their own engine that can be played on Windows or Linux.

Integrate Chromecast technology to make a console like multimedia device to compete against XBox and PlayStation. Then, start selling video and integrating streaming access.

Push the Steam Store to become bigger. Sure, you aren't forced to use the Steam Store on most Valve developed hardware, but it is default.

Then, like Google did with Android, pull the tech stack from the open source tools to become wholely integrated with Steam Services.