Ironically, it may turn out that what appeared initially to be one of Scala's greatest strengths, the close integration with the JVM, may be its undoing. As a richly multi-paradigm language Scala is complex enough as it is, but the various warts and leaky abstractions it inherits as a citizen of the JVM make it that much more perplexing.

Perhaps the idea that Java programmers would find it an easy first step into functional programming was incorrect, and in fact those bold enough in the first place to dip their toes into FP would prefer a cleaner and less compromised view of FP as provided by Haskell, OCaml etc?