OS X, iOS, and all new APIs consumed by Swift on those platforms are written in Obj-C or C++, never in Swift. So what's "stagnant"?

It's true that few others have adopted Objective-C, GNU & MS occasional efforts aside. Which is why I keep a number of languages in practice.

But fragile, power-hungry, slow-compiling Swift isn't going to beat out stable Java, or easy JS or PHP on servers, and outside iOS/OS X, building desktop software needs UI toolkit support and stability.

Which is my point: Building in Swift is total technical debt.