This is an overly simplistic take.

Java hasn't taken that much from Kotlin really, sometimes even gone in a completely opposite direction (for instance with Loom).

Java has taken a few things from Scala but I would hardly call them the best features. Java will never adopt what truly makes Scala stand out, on purpose.

While java has evolved a lot, I still find it hard to go back. The stream syntax and similar things will never match how easy it is to do proper functional programming in Kotlin. I do miss real pattern matching, though.