2017 Rust Roadmap
I would love to see Rust with a REPL.  I use Python professionally a lot and have done a fair amount of OCaml in my spare time and both have excellent REPls in the form of `ipython` and `coretop`.  Quick experiments with auto-complete is incredibly helpful for exploring a language.  That's the only thing I really miss from those languages; when I want to wrap my head around a bit of syntax or a library feature in Rust, I build out a quick little experiment and see if it compiles and behaves as I expect it.  With a good enough REPL, that's unneeded.