Canonical today revealed that it is dropping official Ubuntu Touch support for the Nexus 7 (2012) and Nexus 10. The team will instead focus on providing better official support for just two devices, Nexus 7 (2013) and Nexus 4. Word is that Nexus 5 might never be added, but the community should take care of that soon enough if that us the case..
The good news is that unofficial support won't be stopping anytime soon. Individual developers and collaborative projects have brought Ubuntu Touch to 50+ devices, and we can expect someone to carry on providing unofficial ports for the Nexus 7 (2012) and Nexus 10 despite Canonical backing out.