While modern JVM languages leverage Java to overcome the 'library problem', the traffic tends to be one-way. So while there are 'clojurely' ways to call Java libraries, calling Clojure from Java is ugly and non-idiomatic, despite what the article claims. How does one even call Scala from Clojure?

Presuming that, for the most part, developers migrate from Java to a different JVM language, then inevitably these languages will fragment code written for the JVM, devaluing the very foundation used to hoist the languages into usefulness in the first place. The tower of Babel will rise higher with competing idiomatic implementations of various libraries. This is not a bad thing--rather it has to be this way because introducing new language features (such as STM in Clojure's case) demands it. We're living in a gold rush on Java to mine it for its libraries. After this will come a period of settlement as each JVM language builds its own community, with civic structures that perform the same duties, but look different, in every town square.