Parallel concurrency is the Great White Whale of our time. Languages like Python and Ruby give you a toothpick to hunt with. Java gives you a letter opener. Go gives you a decent bowie knife. Clojure gives you something like a proper harpoon. But something eventually has to come along at some point to make it possible to not have to take down Moby Dick in the first place. I don't know what that is but I'd love to see it.
There is quite simply no argument that Java doesn't provide better complex concurrency support than Go. You can argue that the golang defaults are better, but there is nothing you can do in go that you can't do in Java and quite a bit the other direction that reverts to "program C with FFI".
