My personal take is that the next major milestone for Erlang/Elixir will be a significantly more performance BEAM. Be it JIT or reworked Hipe.
Elixir (& Phoenix) brought a ton of interest from the Ruby community. The only remaining aspect that would keep a Ruby developer using Ruby is the perf vs Erlang. Today, for many raw perf task there isn’t a meaningful difference in speed (note I’m not taking scalability). As soon as the speed difference becomes meaningful, Erlang will get another wave of people.