I can't talk from a consumer perspective, but from a developer perspective, they need to open source everything .NET-related if they want to remain relevant.

With Ballmer gone, if people like Hanselman and ScottGu gain more influence within the company, I'm sure we'll see great things being open sourced.

It's hard to shift the company to open source with someone like Ballmer at the top, it would be like admitting defeat to the open source movement, and people in such positions of power never like to admit they were wrong in their strategy. It's human nature, I almost don't blame him.