I'm sure the push for Kotlin probably has something to do with the bitter lawsuit they're currently embroiled in, rather than a particular love for that language.
Of course in hindsight buying Sun would have been better for Google.
What about go-lang and dart?
Dart is not popular.
From my point of view, Google chose not to buy Sun because they hoped that Sun would just burn to the ground and as such, they would get away with the way they approached the whole situation.
On the other hand if Google had bought Sun, we would still most likely be stuck with Java 6 and just runtime improvements, if at all. If Go and Dart are any examples to go for.
There was no way of knowing the farmer who'd buy the cow would claim goat milk infringes cow-milk protein IP (apologies for stretching the metaphor beyond breaking)
It isn't even as if they don't have their own languages.
C++, Dart, Go, just pick one and provide a migration path.
Don't sell Java compatibility and promise that even with #KotlinFirst, Java and C++ are still relevant for Android. As they did at Google IO 2019.