Regarding Josh's prediction for Android development: I don't think there is the need for Google to provide a counterpart to Swift. We are in the Java world and so we already have the choice.
I guess one hot candidate is Kotlin: JetBrains recently released Kotlin 1.0 (after a few years of public beta). Kotlin is a nice functional programming language which addresses exactly the pain points of Java (functional programming, null-handling). Its collections are based on Java's collections. In sum it has a very steep learning curve and the best: It comes bundled with the official Android Studio (which is also from JetBrains), so that it is a drop in replacement for Java and works out of the box.
Besides this Scala has become very usable for Android projects. Thanks to gradle-scala-android-plugin (https://github.com/saturday06/gradle-android-scala-plugin
) which hooks into Android's Gradle-based build system Scala projects are now easy to set up. In conjunction with multi DEX support turnaround times using the emulator are comparable to pure Java projects (besides the compile time...).
My Android podcast player uPod (http://upod.mobi
). is written 100% in Scala. When I started in 2013 it really was a pain to get the Scala stuff up and running on Android, but nowadays it works fine (beside some glitches in IntelliJ).