Why does everyone keep talking about a subscription model and update fees? It's not like Windows is the company's only product. It'd make sense to give it away for free (at least to home users). Basically it's a conduit to endless other revenue streams from selling developer software, bing, xbox, office, and everything else MS has in its portfolio.
I hate to use a crApple reference, but it's like giving iTunes away for free so that people are coerced to buy content from iTunes and use inferior hardware like iPads/Pods/Phones/macs.