In addition to what everyone else has said, don’t forget there has been lots of interest from people wanting to replace the Rails Discourse backend with Phoenix/Elixir, here’s one such thread:
Also @hubertlepicki is right about the hosting. I actually bought the domain in June 2015 (shortly after I started the Ruby forum) but kept putting it off because setting up multiple Discourse forums on the same server just seemed crazily complicated. I even had to get a new server because Docker wasn’t supported on CentOS 6. Even now we need custom firewall rules because every time our custom security software updates (and restarts the firewall) the docker container loses connection to the internet - so social logins break, one box break etc.
Having said that, from a software vendor’s perspective docker makes things significantly easier because they only have to support one stack - theirs. (This also highlights another Elixir/Erlang strength - you don’t need redis servers and what not, Erlang & Elixir can do it all.)
On top of all of that, I think competition is good because it helps drive innovation 
it’s not going to be easy displacing Discourse, it is really good software made by a really talented team… so I’m eager to see what Josh and the Firestorm team come up with 
