Well maybe even later, yes that's right lets take a step back at all the hullabaloo of the mighty Microsoft muttering like a drunk uncle at a bar mitzvah something about Open Source.
The road would be a very long and bumpy one, throwing open the doors to the complex code behind the worlds largest PC operating system platform. In a weird way I can understand why they would after looking at the success of Android and of course now the Open Power Foundation seem to have found a way to battle Microsoft in the Data Center too.
Before all that code is out in the public domain, they have to get to a stable release - I'm not sure you can call 3-4 weekly service packs trying to fix and fire fight viruses and vulnerable code as a stable release. You also have to question, the code would have to be without gaping holes because I'm sure if the code was released now, every company would have its data stolen within hours.
All that fixing takes time and energy, all those dollars spent to give your product away, and I highly doubt devs in the open market would want to do it, its too big a job. Maybe they could hire some cheap labor, lets face it thats exactly how they built their empire anyway.