Microsoft's head of devices, Julie Larson-Green, has foretold of a future where there aren't three versions of Windows. Most journalists are taking this to mean that Windows RT is at the end of its short and pitiful life. I think this is bigger than that, though: This is confirmation that all three of Microsoft's operating systems are going to be killed off, replaced with a new, consolidated and unified OS that spans phones, tablets, laptops, and desktops.