Why don't they just call it a new framework if its undergoing such a major overhaul. This only makes me feel better about picking react at my current company as now I view this framework as dangerous for building anything long lasting.
This is one of the things that made me dislike angular. If your are changing the entire API and syntax then it's a new framework. Don't steal the name of an existing framework just to steal the SEO. It's dishonest and makes it harder for users of both frameworks to search.
The React ecosystem introduces huge breaking changes and paradigm shifts literally all the time... coughreactroutercough
Reactrouter is a 3rd party npm package... the core react framework has been very stable and backwards compatible.