What major concurrency models will be supported long term by the KotlinX Coroutines library?

Can you be more specific, please, on what “concurrency models” you are interested in?

Actor, which you might have seen mentioned in a post I made in #coroutines ( https://kotlinlang.slack.com/archives/C1CFAFJSK/p1583805157272700 ). Other concurrency models I am interested in are CSP, and Worker. Will the Worker model ( https://github.com/JetBrains/kotlin-native/blob/master/CONCURRENCY.md ) be confined to Kotlin Native, or will it be accessible on other Kotlin platforms (Kotlin JVM, Kotlin JS) through a separate library?

All are supported and will be supported. They are nothing more than coroutines connected by channels in certain model-specific ways.