If Carbon ever goes beyond an experiment it will be for Google's own internal purposes.
What's wrong with that? All of my gripes with Java, other than the way they did their generics, are at the language level. The bytecode and underlying VM are works of art. Kotlin adds reification to the JVM and adds explicit nullability annotation as a compile time error rather than a warning, which solves my worst annoyances with Java. I'd still use Kotlin if all it did was transpile itself into .java files and call the compiler for me.
Kotlin also decided to become a platform of its own, just like every guest language.
It is also the reason why despite my C rants, if there is no alternative, that is what I use.
I rather use the tools that ship in the box than adding additional layers to configure and debug.