My first suggestion would be Swift, which I think will enjoy an exponential use curve going forward. That will also give you exposure to a highly efficient nati

My first suggestion would be Swift, which I think will enjoy an exponential use curve going forward. That will also give you exposure to a highly efficient native language, in fact one that's quite a bit more efficient than Go. It's also very well designed, and doesn't come with the learning curve of Rust. Finally, it will position you to do iOS and macOS development, which you may find enjoyable and profitable. I see you're interested in Linux from an earlier comment - Swift is open source, with a Linux port. Otherwise I'd probably suggest something on the JVM ecosystem, if you might consider either portable web development or Android development. I personally find Scala, Kotlin and Clojure to be interesting in the JVM space.