I want to see a clojure clone embedded as a Go scripting language. The immutability means that the interpreter would be mostly threadsafe, and thus would support goroutines well.
Embedding an immutable language in a mutable one is a recipe for awkwardness - how would you expose host-language things to the inner language? Better to do it the other way around - mutable scripting language embedded inside immutable host.
Calling Clojure from Java is not remotely what I would call beautiful; it's a lot of Strings and pain (especially when you compare to calling Scala from Java). Calling Java from Clojure is substantially more elegant (it requires a structured FFI but Clojure is good at those).