This is Microsoft's strategy: 360 Experience
"Nevertheless, Microsoft is taking a giant step towards a future where developers can write once and run everywhere (Windows, Windows Phone, Xbox)"
This is Microsoft's strategy and Apple and Google still haven't figured it out. They will create a true 360 degree experience for users with Windows PCs, tablets, phones and consoles running the same apps and the same UI.
People will get so used to live tiles, Metro UI and being able to run the same app on Xbox, Windows Phone and PC that they won't feel comfortable with old-fashioned icons anymore. Basically that would kill iOS unless they make something that feels like live tiles without copying Microsoft's Metro UI. And here's the catch: Microsoft probably has all kinds of patents on Metro UI barring Google and Apple from using the same concept => People will start thinking that Apple and Google use an old-fashioned interface => Microsoft gains market share.
Soon websites will also adopt the more simplistic design language of Metro UI making Apple and Google operating systems feel even more out of touch. And by 2015 you will think how on earth you could live without Metro UI.