First I looked at Java - mainly because it is the language for making Android apps. But I have found, that I do not like the language and I do not believe in its future.
Then I played a little with Go. If I intended to learn a new language just for fun, then I would decide to learn Go. The syntax of Go is very comprehensible to me and I like the language. But Go does not seem very promising. It can be used on Google app engine and I can install it on my desktop or server. But it is not what I'm looking for.
- Dart will be integrated in Chrome and if it is successful, then it will spread to other browsers as well.
- If I interpret correctly this answer at I/O conference, it is possible to expect Dart language support for Google app engine.
- I suppose that Google will bring Dart language support at least for some of its projects, like packaged apps, native client, apps script, or even Android.
- The Dart community is pretty active.
No one knows if Dart will be successful or not. But I decided to start to learn the language. Maybe the uncertainty of the Dart future will stimulate me to learn more intensively.