According to Stack Overflow Developer Survey 2018, Kotlin is the 2nd most loved language and the 4th most wanted worldwide. TechBeacon also took it in the list of 5 young programming languages with a great future.
Many developers now are moving their projects to Kotlin. In speaking of famous ones, I can name Pinterest, Uber, Coursera, Trello, Evernote. I work in the company that uses Kotlin for Android dev, and Java - for maintaining old projects only.
JetBrains created the language so that it could work everywhere where Java works, implement the same tasks much simpler while writing short readable code.
Java, surely, is a good language for building Android solutions. So, there are a lot of questions like should they move to Kotlin, should they combine both technologies, is Kotlin better than Java, and more.
Android development with Kotlin language: Kotlin benefits, features, the latest updates.