Really, open source is growing faster than it ever did before, the products are getting much better, they're slowly wising up to the fact that open source does not mean 'shitty support' or 'no need for marketing'. More and more people are finding ways to make money in open source projects.
Drupal got a very large amount of funding based on software they're giving away (ok, not my personal choice, but still).
And so on. Open source is maturing, and microsoft could do a lot worse than set a trend for a change instead of trying to hold on to the brakes as hard as they can.
The examples you give are all tied to very specific hardware, microsoft thrived on open hardware making tools and supporting those tools.
Look at where IBM is going for what microsoft could be like.