The team at Canonical has announced changes for Ubuntu Touch regarding the devices that it will be compatible with. The mobile version of the popular Linux based OS will only support the Nexus 4 smartphone and the second iteration of the Nexus 7 tablet. It is believed that the OS will be able to be ported to the much newer Nexus 5, though there won't be any official support. Other devices that had support dropped include the Nexus 10, the first Nexus 7, and the Galaxy Nexus. The first version of Ubuntu Touch is expected to be available at the end of this month, and the Canonical team is spending a lot of its focus on the upcoming Long Term Support version of Ubuntu that will be released in April 2014.
Source: The Droid Guy