They revoke the React patent grant, which effectively downgrades "the React license" to just a stock BSD 3-clause license. At that point they will likely counter-sue you for patent infringement.
In my mind that situation is effectively identical to losing "the right to use" license on grounds of patent suit (like Apache). Interestingly, in Apache you'd still be sued for patent infringement (not copyright infringement) because "right to use" is provided as a patent license.
> They revoke the React patent grant, which effectively downgrades "the React license" to just a stock BSD 3-clause license. At that point they will likely counter-sue you for patent infringement.
Yes, but for what patent? People have looked; none have been found. :)
Patent applications are secret, not to mention that software patents can be very difficult to interpret and search for. RMS gave a fairly long talk about the various problems with software patents[1], and the difficulty in being able to find all software patents that may be related to a project is one of them.
Patent applications are public for a minimal time period, 18 months at the very most. But obviously patents are public. React has been open source for over 2 years now. It's highly-likely, almost certain, that any React-related Facebook patent would now be public.
The second part of my comment is probably more applicable (maybe I should've just excluded the point about private patent applications). Even if a React-related patent was public, it wouldn't be called "Patent on React Framework". It probably wouldn't even use the words JavaScript, HTML, or DOM. You would need to hire a patent lawyer for an extended period of time to have a reasonable amount of certainty that no such patent exists (and even then, it's just an educated guess).
In my mind that situation is effectively identical to losing "the right to use" license on grounds of patent suit (like Apache). Interestingly, in Apache you'd still be sued for patent infringement (not copyright infringement) because "right to use" is provided as a patent license.