This is one of those cases where it doesn't matter that much. World domination is overrated. The JVM's prevalence largely takes care of platform availability. Java interop ensures enough libraries will continue to be available for use. And Jetbrains' internal use of kotlin on a large codebase ensures the language's sustainability. What more is needed?
I would want to see a bigger adoption and companies start using it more often, so I can use it in more projects. I really like using it over other languages.
Every time I write java I think: I would had spent less time writing this in kotlin and the code would be more readable.
Every time I use a non-statically typed language and have a bug because of it I drop a tear thinking that I would never had that bug that took me a couple of days to find in kotlin.
Oh sure it would be nice to see it adopted more widely. I just mean it's not in the vulnerable position of most new(ish) languages. Kotlin is ready for use in any suitable project by anyone who likes it. Though I'm a bit raw with it as yet, I love it for Android. Look forward to seeing the javascript & native possibilities.