Java is a massive object at rest in many IT departments. I just don't see these dynamic languages having enough force to unseat it. Make it budge, fill a niche, find adoption in progressive teams, be introduced on the "down low" on small projects... ok, but not a wholesale replacement.

Adoption of languages and frameworks is more about being "good-enough" at the right time. The longer a "good-enough" solution stays in place, the more compelling a better solution has to be to unseat it.