Yesterday's Who is hiring? (https://news.ycombinator.com/item?id=7679431) only had 1 mention of Groovy or Grails (and none of Gradle) out of over 400 comments. And many (most?) of the projects tagged Groovy on Github are triggered by a single Gradle build script for a project that uses some other language. These Gradle build scripts are often 30 lines long.
So I'm not sure how Groovy will fare in the future. Nothing seems to be taking its place, though, for testing and general manipulation of Java classes. Java and Scala are statically-compiled languages for building things, whereas dynamic Clojure seems to also be used for systems programming rather than scripting. I'm guessing Oracle will heavily promote Nashorn for scripting and JavaFX, but Javascript syntax doesn't seem quite as full-featured as Groovy for now.
Back in 2009 there was a big Grails wave here in Germany. Many JUGs had Groovy and Grails talks.
There was also some people trying to use Groovy with JSF. Myself I attended a session promoted by Sun hitting at possible official support after the JSF 2.0 release.
To the point we added support to it in our in-house JSF framework SDK, still JSF 1.x based.
Since late 2010 I have been doing .NET land mostly and now back on Java land, I hardly see any Groovy besides Gradle.
There was a Grails wave here in Germany, but now I seldom see anything related to it.