C++ and Objective-C both started out as preprocessors of C. So feel free to define the line where a language extension becomes its own independent language. But for me, that line exists where the dependence upon the parent language ends; just as it did with both C++ and Objective-C.
At present TypeScript is defined as a superset of JavaScript and is therefore just a broad extension of it. Until its popularity and usage spreads to the point that a full interpreter arrives capable of removing its dependence on JavaScript, it is not a separate language and JavaScript is not "dying."
That is my point, and it's not that big of a difference if you understand my historical context. View Dart for more failures of this exact nature.