[jpgvm]

There is also the matter that between Clojure (a Lisp), Scala (an ML/FP/fraken-language), Kotlin (multi-paradigm/"modern syntax") there isn't a lot of space for new JVM languages to explore right now unless you were to build something like Pony or Erlang/Elixir that leveraged the new Loom runtime.

Most of the popular paradigms (with Java taking the "C++ alike" role) are already serviced effectively by existing langauges.

[tadfisher]

Haskell on the JVM is a well-explored niche with lots of working but abandoned projects (Eta, Frege, etc). Getting a JVM backend into GHC would fulfill the "pure/lazy/FP" space, which is notably absent from your list.

[jpgvm]

Oh that is a good one too. I would actually kind of dig that if one could get off the ground.

[zem]

Ceylon came out at around the same time as kotlin; for a while they were both good contenders for "a better Java that wasn't too different"