Rust and Go are very different languages, with very different aims and objectives. They are often mentioned together, as a few years ago around about the time Go went public, they both talked of themselves as 'Systems Languages'. But they meant very different things by that.<p>Ruby is not a language that would ever be used for writing a web browser, Virtualmachine, OS kernel, or other high performance low-level software.<p>Nor is Go.<p>Rust is.<p>Ruby and Go are languages for writing servers, web apps, 'scripting', and high level stuff.<p>Rust has the interesting property that it may well be possible to write relatively sane higher-up-the-stack server software, in the land that Ruby and Go currently are popular, but it's not there yet.<p>If you want a replacement for Ruby, and don't want to use Go (for whatever reason), then I'd really advise asking "Why?", first.<p>If you want to learn and grow as a programmer, then learn a bunch of languages, and don't get too hung up on whether or nor they'll last. There's a good chance that in 20 years time we'll all be using something totally weird and different, so learning a bunch of different ways of working and learning to think in different terms from Ruby may be more use than any specific language. Learn Haskell, Rust, Racket, Erlang, Assembly, Forth, Ada, Fortran, C, D, Clojure and Scala, say.<p>If you want a very practical language for writing server stuff, quickly and without having to learn too much new stuff straight away, then maybe look at Elixir, Kotlin or Ceylon.<p>If you're happy with Ruby, then there's no real reason not to stick with it. It's a good language, and a lot of fun to use. (Elixir is superficially similar, if the aesthetic of Ruby code really appeals to you).<p>Rust should be pretty easy to write extensions for ruby in, so if you want to try branching out into Rust, for doing high performance / low-level stuff, then give that a go.