With Kotlin on the JVM and Kotlin Native on Windows, Mac, Linux and iOS I really don't see much of a future for Swift outside of iOS. Kotlin, though, will be everywhere.
I think both will find their place. Currently there are many languages that are interchangeable in many cases and yet they find their users.
I suppose that Kotlin outside of JVM has a similar problem to Swift outside an Apple platform. You lose a support for quite a lot of already existing libraries. Rewriting everything in Kotlin and Swift will take effort and by the time we'll get there not many will want to abandon their preferred ecosystem.
