Ask HN: Is ruby/rails still a good bet? What else should I learn?

I've worked with ruby and rails (and other ruby frameworks) for many years now, mostly for backend works, and I love them. It's the only language I'm really fluent with and I'm thinking about looking to some more languages to deeply learn and experiment, to avoid that one day ruby won't be needed anymore and . I'd still like to be on the web development Which languages and frameworks do think are good bets? Javascript (nodejs, angular/ember, and many more)? Go? Which others? With all the client javascript frameworks I'm also starting to wonder if we'll ever need backend anymore or if it'll be just built as "premade blocks" and bringing all the focus to the frontend