Forever. Or did you mean by Typesafe? It depends on the business case, but I think it's safe to say 2.9's lifespan is a good indicator. We hope to provide more frequent minor releases in 2.10, especially if we decide to require Java 7 in 2.11.
- What features in Java 7 besides invokedynamic would be beneficial (or are planned) for Scala to depend upon?
That's the big one (faster closures, potentially faster structural types,...).
Not having our own fork/join jar in the dist will be a nice bonus.