[halomru]

>A potential patent applies to any implementation. Even if you write a clean-room clone of React, if it uses the same patent, Facebook has a patent claim.

Sure, but that only rules out a reimplementation of React. The question most people face is "React or existing alternative X?". If your chosen alternative is still actively developed, it's probably notably different from React in concept and implementation (why else would it still exist).

Now if Facebook owns any react-related patents, you use all of them by using react, your alternative has a good chance to be sufficiently different to not be infringing.

In terms of your chances of using Facebook patents, any alternative is strictly better than React itself.