Maybe neither of us are privy to Microsoft's innermost strategic decision-making processes, so neither are qualified to comment on whether they've thought this through?

That said, I would argue it is more efficient to expect that one of the world's largest companies would think very carefully about its options before making such a huge leap.

One more thing: remember that Microsoft is not gambling on the current Windows 8 UI paradigm itself. Not exactly. Microsoft is gambling on the general style: clean, clear typography matched with bold blocked colour and clear, simple iconography.

Take a look at http://www.microsoft.com/en-us/default.aspx.

Granted it's not perfect, there are still hiccups - the search magnifying glass for instance. I expect those hiccups to be ironed out soon enough though. Regardless, what Microsoft is effectively doing is staking its claim on a visual style, which it clearly thinks will be prime real estate over the next decade. I think it'll pay off handsomely. At the very least they've wiped the slate clean and laid a foundation that will be much easier to tweak in future.