I think one flaw in your analysis is that Flutter is not analogous to "Java in the enterprise": it's already very pleasant to use compared with modern web frameworks.
Meanwhile Dart has adopted all the features I dislike in Java, like @Override instead of proper keyword, virtual methods by default, no value types and so forth.
One of the major pain points of Android development is that the vast majority of the API is designed around limitations of Java 6. Yes, I know that you can use most of Java 8 for Android now, and Kotlin is pretty good. However, it took far too long for Google to deliver that to developers.
However, Java 9 support is already ongoing on AOSP, so we might still get some good news by Google IO 2019.
In any case, even if Kotlin turns out to be the future of Android, it is much more worthwhile language than Dart, in features, backends and CV value.