I don't think it's necessary for a language to be in the top 10 to be considered a success. If the people who use it, wouldn't use anything else, then that is the success.
As long as you're aware that hiring and maintaining will be significantly harder then yes you're right. But that also means there's no reason to choose esoteric tech X for yet another CRUD app; you would pick Erlang/Elixir when it actually makes sense and only then.
