Um. You should change your title to “Understanding static in React and possibly future versions of JS”. Static properties (not methods) are available in React, because of this Babel plug-in, which is a precursor to this ES suggestion (which is not yet implemented).
So, in ES6 there is no such thing as a static property (yet), as you can see in the article you referenced at the end of your post. There are only static methods.
It is also important to note that proper static methods ARE NOT shared with the objects created by the class or function they are a member of, unlike the static properties within React/ Babel transformed classes. Your article is mixing some things up that needs un-mixing. :-)