Kotlin itself is largely dependent on Java. So Google needs a completely different alternative which helps them get rid of it entirely (That’s one of the reasons for the existence of Fuchsia). The Dart programming language used in the Flutter framework is one of the first steps taken by Google to do the same.
I am still thinking between Reative Native and Flutter. Actually I prefer developing an app using a native code. So recently I looked through Kotlin and Android native platform. By the way it seems that Google might give up Kotlin in the future in according to this article.