Was hoping for golang but this is good too
Go is going to have better support on Fuchsia OS from Google.
What I am not happy with this whole browser platform embedded in frontend apps and called native and amazing. But that's for another discussion:-)
I'll keep writing Java to build Android apps though. I'm sure it's "more fun" or whatever, but Java's worked just fine for me thus far. I'm used to the verbosity, and have no desire to start from scratch with another language. If some huge benefits were presented, I would. But, I'm failing to see any.
Kotlin, however, interops with Java nicely since it compiles to jvm bytecode. So there's no new APIs to build and no transition performance costs.
Although that said you can actually use Go on Android ( https://github.com/golang/go/wiki/Mobile ) but since Go is native code you're stuck with Android's NDK or dealing with JNI and the performance costs of that.
Go doesn't seem to be used that much other than a few known projects like the stuff that got re-written for YouTube or the download server.
You see this when new Web APIs are released, usually Go isn't part of the preview SDKs, and on Android all the work done on Go mobile has been done by people on the Go team or from the community at large.
Regarding Go at Google, if you have better sources of information to share with those living outside Mountain View, it would be very helpful.
Many of the important devs on the V8 team, like Gilad Bracha, were getting tired of working on the project and started to look elsewhere for a career change.
Allowing them to create their own vision what a JavaScript replacement might look like (aka Dart) motivated them to stay on the team and at Google.
When the Chrome team decided that they wouldn't be merging the Dart VM into Chrome at all and would rather focus on JavaScript, including their efforts for adding type annotations to JavaScript, the Dart team was going to be assigned new tasks.
However in the meantime the AdSense team had started using Dart and they enjoyed using it quite a lot, so a decision was made to move the Dart team away from Chrome into supporting the AdSense team as main role.
If this is not true, I would welcome any Googler that knows better, to correct me.
On android, everything gets AOT compiled on install already.
1) interoperability between existing ecosystem and APIs
2) development environment support.
In case of Kotlin Google had to do nothing: Kotlin is 100% interoperable with existing Java code and libraries, including Android APIs; as for the development environment, JetBrains (the company behind Intellij IDEA and Kotlin itself) provides the same level of development experience for Kotlin as for Java, which means that Android Studio gets the very same nice features for Kotlin.
Now, how would they get the same with Go? For interoperability they would need to either generate tens of thousands of bindings for existing APIs and provide a convenient way to include compiled Go binary as a static library. It is highly doubtful they actually can do, since they have been having troubles to do it for C or C++ code for a very long time. Or as alternative they can improve their support for native code, which then can be used as a base for interoperation with Go code; however it is still considerably less pleasant way to do things than in case of Java + Kotlin.
Now, as for the development environment, Google will have to basically create yet another IDE on top of Android Studio to support Go; they might take an existing plugin (which is not that great, compared to Kotlin support in AS/Intellij), but it means that they would have to collaborate in development on it, which in case of Google takes too much time. Another indicator of how difficult for them implement at least someway decent support for another language on their own is situation with native code - it's being in development for like 3 years, and still is highly unusable.