The disaffection of ex-Java-devs towards these newer JVM languages is only really surprising if you were expecting any other language to overtake Java for Java developers. I used to think that would come to pass, but I've been convinced otherwise.

By the time Java 8 comes around (don't expect Oracle to drag their heels on releases as prior regimes have), there will be little inherent reason for the typical Java developer to use Scala or Clojure. Only the biggest vendors (Oracle, Microsoft, IBM, et al.) have the firepower and perspective to produce/support whole-solution languages and ecosystems that go mainstream with tooling, training, and general-purpose facilities approachable for the vast middle.

That is, the next Java is Java′.

Of course, none of those typical devs are reading this or TFA. The real question is, which language is most applicable to particular problem domains and usable within particular organizations by atypical devs solving atypical problems? (Added bonus goes to the language that makes bidirectional interop with that vast middle of Java devs a piece of cake, for those atypical devs looking to provide libraries, tools, and products to be used by those Java devs.)