Elixir looks interesting, but the issues it addresses in Erlang are mostly superficial and subject to taste; eg I like single-assignment, and consider 'nil' a deficiency that can usually be avoided with proper typing. But each to his own -- Erlang does have its quirks, but for me, that mostly fades once you're neck-deep in code.

I'd like to see a BEAM-based language designed with an eye towards advancing the tenet of fault-tolerance in ways Erlang currently can't. Probably the most significant weakness right now is with the type system -- lacking exhaustive checks for pattern and function matching always makes me nervous, since that's probably the most common source of errors in my Erlang code.

Rust looks promising in this regard. If a best-practices framework emerges a'la OTP, Rust is going to be the dream love-child of ML, C and Erlang.