I think a nice situation would be to have all the core scientific libraries and tools written in rust with clean APIs, independent of any particular scripting language but with the clear goal of providing a clean API to wrapper languages. Then any scripting language can wrap these libs and go - essentially something like a universal numpy/scipy/scikit, etc. This would mean Ruby/Python/JavaScript/Julia, etc. would all be able to get to state of the art immediately while minimizing the duplication of effort across languages and creating a standard "ML" or "Scientific" API.