Building apps is one thing, JavaScript is another. There's an intersection of both that people make apps in JavaScript. React is one way of building apps and we already see it in Web apps, in Android, in iOS, in Desktop, in Windows apps. So React is based on JavaScript and it's an implementation. I guess React may die one day very far from now. But the ideas come from React will live longer than that.
I think JavaScript is bad language with many nice features, you can choose a better if you have a choice. Meanwhile you need to be sure you can handle them problem in using React with enough JavaScript knowledges.