Android has been installed on various devices, including smartwatches with low-resolution display, smartphones with up to 1920 x 1080 pixels display, and tablets with up to 2560 x 1600 pixels display. It means that the operating system must support various pixel densities, from 120 ppi (LDPI / Low DPI) up to 480 ppi (XXHDPI / Extra Extra High DPI)
Through a deep exploration, source code in Android 4.3 Jelly Bean is known to support 640 ppi pixel density (XXXHDPI / Extra Extra Extra High DPI), that means it supports up to 4K resolution. Will there an Android device with 640ppi pixel density? Actually, a mobile device with 480 ppi pixel density like HTC One is too excessive. It seems that 4K resolution will be applied on Google TV.