Desktops as we know them are going away. We are seeing a trend toward increased reliance on mobile devices, even at the desk.
There are two main operating systems on those mobile devices, iOS and Android. Android has about an 80-85% share of the mobile market worldwide. iOS is around 12-18%, depending on who's doing the study.
Five times as many mobile devices as PCs are sold each year.
Android has, at its base, a Linux kernel. Sure, the hardware doesn't look anything like a desktop machine; Android doesn't look like a traditional Linux distribution; the update and application management is different; and the applications are different, but it's still Linux.
When Android and ChromeOS devices become the platform of choice, we will have achieved the Year of Linux on the Desktop. Maybe we already have.