I think that this is a good question, but poorly phrased; you assume in the phrasing that it's possible for the existence of one language to "kill" another. I

I think that this is a good question, but poorly phrased; you assume in the phrasing that it's possible for the existence of one language to "kill" another. I was somewhat disappointed when Apple shipped Swift; I feel like Rust has considerably more potential as a general purpose language, and it would be nice to have less dilution of effort in fairly similar space. However, I don't think that the existence of Swift is an existential threat to Rust. > Swift will be able to do everything Rust can do and is also positioned as a systems programming language Swift is an interesting language, with some good ideas, and in many ways easier to use for application programming than Rust; but I still, on balance, think that Rust is more interesting and versatile. Swift is not really a systems programming language. You can't write a kernel in Swift, nor target embedded platforms, nor write a library that could be called from other languages like Ruby or Python (at least, without bringing in the whole runtime as well). It's closer to the space of Go, a more systems-y application language. Furthermore, open source Swift does not mean you will be able to use the whole ecosystem on other platforms. I highly doubt that Apple will port Cocoa/Cocoa Touch to other platforms; so Swift on other platforms will likely only be viable for back-end code. Objective-C has been open source for years, and until the introduction of Swift was the dominant language of choice for writing code on one of the most popular smartphone platforms, but Apple canned cross-platform OpenStep when they bought NeXT, and Objective-C has never made serious inroads on other platforms (I know exactly one person who writes production, server-side code in Objective-C on Linux). So, I could see Swift becoming popular for writing backends for iPhone applications, but I can't imagine that it will make serious inroads in other spaces, unless Apple makes a dramatic change in strategy and starts shipping their UI libraries on other platforms as well.