Ok, there are alternatives. Canonical has their Convergence with the same idea as Microsoft. My Nexus 4 phone has Ubuntu Linux (brought by Canonical) inside. With bluetooth keyboard/mouse paired with phone and a full HD HDMI -monitor Nexus 4 turns into a PC in a minute! Take a look at the pictures below and my earlier blogpost. The only downside at he moment is there are not that many phones which are able to run Ubuntu Touch.
But are there any really big rivals showing up? There is evidence Google might be interested in adding support for an external monitor and windowed applications in Android. This is good news. The only thing is who wants to run Android on full HD screen? Well, maybe we'll see something like RemixOSforPC which combines Android and ChromeOS. Take alook at the picture below.
Windowed apps on Ubuntu Touch
Bluetooth keyboard and mouse paired
with Ubuntu Touch and Nexus 4
The whole set!
RemixOSforPC combining Android and ChromeOS