This does not mean that Dart as a language is being abandoned. Support within Google for Dart is strong, as the blog post indicates. Google Ads is the biggest customer for Dart. Google Fiber, Google Express and internal sales teams are running mission-critical apps on Dart. Dart still is a great option to have common code on both client and server sides, and the engineering team will be focused on enhancing the virtual machine and tools with a clear focus on the Web.
In related news, the Dart 1.9 release has brought a series of features that position it strongly on the server side. The release features strong support for asynchronous programming along with an updated regular expression engine (150x faster), Isolate API, full enumeration support and more. Check out the full release notes.
The future of Dart will definitely be a topic of discussion at the upcoming Dart Developer Summit, to be held on April 28-29 in San Francisco. There is no doubt that Dart is a nice language with developer productivity, clean syntax and code sharing among its many goals, but getting developer traction outside of Google has been a challenge. This year is going to be a defining one in its journey.