It's very interesting to see the data for what technologies Java developers are "really interested" in:

Scala: 47%

Java 8: 35%

http://zeroturnaround.com/wp-content/uploads/2014/05/what-te...

Java developers seem really interested in Scala (more so than Java 8). I think the distinction which will come in when comparing technologies that developers want to use and are really interested in vs those that they will actually use given inertia of existing code and corporate adoption.