Highly unlikely. Why wouldn't they also reject rust, c++, or anything else that isn't swift or objective-c that compiled down to machine code with llvm? If anything, Xamarin would be first. It's a totally different language with a VM. Then there's anything using js (react native), and then of course flutter. Then the huge pile of "other" option (gomobile, rubymotion, etc), and then my crazy personal favorite, j2objc, which is objective c, but is very "googly", and if apple was going to ban things purely for spite, it would be sort of a target. So, outside of apple deciding they don't like kotlin because they think banning it will hurt Google somehow, I can't think of a reason it would be at higher risk than anything else. Apple wants native quality apps, so if anything, they'd be supportive.