I doubt Kotlin is a stop-gap measure, and it does a lot more than just give syntactic sugar for null checks. As the comment above you mentioned it's not only JVM, it has a JS backend and a fully native one which is developing very rapidly. Kotlin and Swift have a very significant overlap in language features, and with how strong the Kotlin community is, I don't see it going anywhere anytime soon. In fact, I would sooner see multiplatform development embracing Kotlin over Swift, given how well it's progressing. Kotlin native hasn't even reached 1.0 yet, and they already made a very convincing showcase of how it can be used to develop server backend + frontend + android + iOS with significant code reuse, and not having to constantly switch language contexts: https://github.com/JetBrains/kotlinconf-app