Exactly. Metro is just a trojan designed to harvest your data.
What they really want is you using Windows Live, getting news from their sites, searching with Bing, using Internet Explorer, play with their XBox, etc.
This is Microsoft's strategy to catch up to Google. If you can't bring the desktop to the web, you bring the web to the desktop.
There's always a new demographic. I'd say Windows 8 will appeal to younger users (those who think the computer was invented for tweeting or for Facebook). It's likely Microsoft has factored this is and is aiming in potentially new customers in the Asian markets, which are predicted to move to the middle class by hundreds of millions in the next few years.
Is it too late? I don't know. People are used to their iTunes for buying songs. The iPhone has sold a lot in China last year (when people don't have the money, they buy the Android). We are all used to Google (and Bing sucks too).
They do have the potential to bring innovation. Kinect could bring a whole new paradigm to interfaces, but we don't know if that's in the pipeline. Apparently, they are pretty much failing with the gestures thing (Apple is much better in this on the new iMacs).