They are going to support the old versions "indefinitely". The FAQ doesn't mention it, but their Release notes[0] does. I'll copy the relevant part here: >We i

They are going to support the old versions "indefinitely". The FAQ doesn't mention it, but their Release notes[0] does. I'll copy the relevant part here: >We intend to keep supporting the 3.x branch indefinitely (published separately on npm to aid in migration), although there will likely not be any future major versions based on that code. 4.0 is the future, but we won't leave you hanging if you want to stick with 2.x/3.x. [0]https://github.com/ReactTraining/react-router/releases/tag/v4.0.0-0 https://github.com/ReactTraining/react-router/releases/tag/v...