Java champion and Joda Time project lead Stephen Colebourne did collect some ideas how the next big JVM language should be. But not Groovy, Scala, Clojure or any other of the new dynamic languages were favored by him. He surprisingly came to the conclusion, that Java will be next succesor.
But not Java as we know by now. He suggests to develop a new Java version from the scratch, not backward compatible but still with the mainstream C-like syntax.
In two follow up posts (here and here) he describes some backward incompatible features in more detail: primitive types, null objects, equals and checked exceptions. Lots of comments were posted with pros and cons. They are also worth a read.