Kotlin is a 'better Java' because of the ability to mix functional and imperative code. Java will never do that. I don't know what you mean about 'IDE support'. Neither of them are going anywhere.
Kotlin is made by Jetbrains which make IntelliJ - so IDE support is a plus-point for Kotlin. That is what I meant.
I think Java has become way more functional over time. It is not and probably never will properly support a pure functional style (e.g. like Scala) but I don't see it much behind compared to Kotlin. Mind to give some examples where Java is behind Kotlin in this context?
