I don't know if one can be fluent only in 3 languages, but I'm in the rank of those who say that learn more will not harm you.
You can reason a lot about, but when you've to learn a new language, just for the pleasure of learning and because it will make you a better programmer, one thing counts: instinct.
I'm often inspired by a blog post, a snippet of code or simply a tweet that sings the praises of something!
I don't make forecasts for the future of a language, if it looks cool to me, I try play with it and see what's going on. (I think you can found practically any REPL on my laptop...)
Anyway I'll give my list of 3:
C# - Because I work with it from beta.
F# - Because I can use .NET knowledge with a functional-first language (and it helps me open the path to other functional langs).
Ruby - Because I'm still a fan of RoR and I love its KISS approach (and a smart dynamic language is useful for various tasks, e.g.: related to DBMS).
Others:
Erlang - It makes distributed computing "easy". I love vanilla Erlang, but other langs of its ecosystem are promising: LFE and Elixir, for example.
Haskell - Knowing it will make you better in every language.
Go - Because it's fun to work with it.
OCaml - Because I love ML syntax and I'm interested in all ML-family langs.
ELM - Because I prefer delegate to a transpiler the duty to write javascript.
PureScript - Same as ELM.
I don't know if one can be fluent only in 3 languages, but I'm in the rank of those who say that learn more will not harm you.
You can reason a lot about, but when you've to learn a new language, just for the pleasure of learning and because it will make you a better programmer, one thing counts: instinct.
I'm often inspired by a blog post, a snippet of code or simply a tweet that sings the praises of something! I don't make forecasts for the future of a language, if it looks cool to me, I try play with it and see what's going on. (I think you can found practically any REPL on my laptop...)
Anyway I'll give my list of 3:
C# - Because I work with it from beta. F# - Because I can use .NET knowledge with a functional-first language (and it helps me open the path to other functional langs). Ruby - Because I'm still a fan of RoR and I love its KISS approach (and a smart dynamic language is useful for various tasks, e.g.: related to DBMS).
Others:
Erlang - It makes distributed computing "easy". I love vanilla Erlang, but other langs of its ecosystem are promising: LFE and Elixir, for example. Haskell - Knowing it will make you better in every language. Go - Because it's fun to work with it. OCaml - Because I love ML syntax and I'm interested in all ML-family langs. ELM - Because I prefer delegate to a transpiler the duty to write javascript. PureScript - Same as ELM.