Since then, Java has incorporated a lot of the syntactic sugar from Kotlin. Not all of it; they're still very judicious about trying to keep the language tight.

Since then, Java has incorporated a lot of the syntactic sugar from Kotlin. Not all of it; they're still very judicious about trying to keep the language tight. But things like the lambda features have even made it down into the JVM (which is actually incredibly stable). Kotlin's one big advantage is having avoided the "billion dollar mistake" of null pointers. Or at least, mitigated it. But in my opinion it's not sufficient to install a whole new language into your stack.