“That’s all you need to know” is very reductive. Never stop learning: add JS and functional languages such as Clojure, Scala, OCaml. You don’t need to use a language every day for it to be useful. Learning a bit of Objective-C taught me a lot about naming variables. Smalltalk taught me about non-class-based OOP. Forth taught me low-level stack operations. Prolog, Io, BASIC, Erlang taught me a lot of things I use everyday, even if I don’t use the languages themselves.