It won't be long before most people have only one computing device: a very powerful smartphone. When used as a mobile device, the interface looks like iPhone/Metro. When you are at your desk, you dock it and the interface that pops up on your 30 inch monitor is like Windows 7 (WIMP). And you can also dock it in a range of shells (for lack of a better word) from a 7-inch tablet (touchscreen UI) to a 17-inch laptop (WIMP UI). All these devices you are docking to are just relatively cheap shells. All your data and processing power is on the smartphone. In fact, even the smartphone will be just a shell, and the computer will be like a large SD card.