- It is not the fastest dynamic language like Clojure or LuaJit.
- It does not have great C interop like Python.
- It does not have an easily embeddedable runtime as Lua.
- It is not the scripting language of all web browsers like JavaScript.
- It does not have major big business backing like PHP.
- It is not as good as Lisps for meta-programming and DSLs.
- It is not amazing at concurrency like Erlang.
- It is not the bleeding edge of untyped functional programming like Racket or Clojure.
- It does not have every library under the sun like Python.
- It is not as great at OOP as Smalltalk
So while it's perfectly acceptable at all those things, it doesn't excel at anything. That's why I think it is loosing ground.
It does have Ruby on Rails, and that's still arguably the best Web Framework.