Kotlin is an interesting option, especially now that it compiles to the LLVM. One of the issues I see is the mind space these languages occupy. Kotlin is deeply linked to the Andriod community which oddly feels like baggage.
Julia has done a great job at marketing itself as the language built for modern numerical computing by numerical computing people. They have effectively recruited a lot of the scientific community to build libraries for it. I think the language is flawed is some deep ways, but there is a lot to learn in how they positioned themselves.
I like Kotlin, but the garbage collector isn't really meant for numerical computing I'd guess, and I doubt having to think about LLVM and JVM and JS at the same time is going to work out well for it when it needs such a heavy, heavy focus on performance.
Julia has done a great job at marketing itself as the language built for modern numerical computing by numerical computing people. They have effectively recruited a lot of the scientific community to build libraries for it. I think the language is flawed is some deep ways, but there is a lot to learn in how they positioned themselves.