Copying my response from AndroidDev subreddit:
I think the better (and less clickbait-y) name for this article would be “The Case Against Kotlin (For Now)”.
Kotlin is officially supported as the third language of Android. JetBrains is an established company, using Kotlin internally, and will continue developing it.
Kotlin isn’t going anywhere and the safety, conciseness, pragmatism, and nice language-sugar are going to win over most good teams over the next few years (as it already has been).
Not to mention Kotlin JS, and Kotlin native. And server-side frameworks all adopting support for it as well like Spring Boot.
I think the real question isn’t whether to adopt Kotlin or not. The question is WHEN, and HOW MUCH to adopt.
- Just do tests?
- Just write Kotlin for new code, and don’t convert what’s written?
- Application code in Java, but new internal libraries in Kotlin?
- Just new projects in Kotlin?
- Take 2 weeks and convert everything?
- Adopt it once it’s been officially supported for X amount of time?
- Adopt when Google starts releasing docs and libraries in Kotlin?
- Maybe you start integrating Kotlin when you make a big hiring push in 6 months and you choose to hire people with Kotlin experience?
These are the questions to ask, IMHO.