In a way this is a good thing, one tool rarely fits all needs (I couldn't curse Java enough for GUI programming). Like C, Java was never designed to be used for developing dynamic web apps, but we still tried and miserably failed with JSP/JSF and plethora of frameworks against PHP/Rails/Python in terms of productivity. One really good thing Java did was to raise a level of abstractions from platform specific details and memory management. These new languages on top of JVM raise the abstraction level even further for its area of strength.
It is not a remote future when we will see concurrent processes being programmed in clojure and presented with jruby/rails with intermediate code written in Java. Each layer of application is going to be implemented in different programming languages while interfaces being transparent for developers working in each layer. This is a big thing, it has never been envisioned before for Java Platform, the lowest coupling we have seen so far is through remoting (web services et. al.) where clients and servers are on different runtimes and languages.
What this means for a Java developer is if you are
- A web developer: you are going to learn things which are extremely different from struts/jsf/jsps, no more artificial model1/model2 MVCs.
- A non web-developer : you are going to write code which is far more readable and very specific to your business domain via DSL created in any of the languages mentioned above without worrying about accidental complexity Java and its frameworks imposed on you.
While I can keep classifying developers on Java platform all day long, these two are major ones whose life (and resumes) are going to change soon, they will be expected to know more than one programming languages rather than frameworks now. Contrary to the cool kids on interwebz, I don't think Java the language is going to die anytime soon not because many of the existing libraries are written in it, but because of the number of programmers on earth who know Java, tooling around it and the native JVM support for it. Java is like C in a way, you can do whatever is supported by underlying implementation.
Many of you who are like me are going to see change around them soon, I am thrilled to see how my career is going to transform as polyglot programmer are you?