So, assuming you actually have a patent, and Facebook actually decides to infringe on that patent, the worst case scenario is that you lose your license to use React. There are principles of fairness and equity in the law that would allow you to stop using React in a reasonable amount of time. So write your frontend in Elm. It probably needed a rewrite anyways.
> the worst case scenario is that you lose your license to use React.
Not even that; you lose your license to use the patents Facebook has which cover React...
...if they exist. Nobodies ever found one, and a core React dev is on record saying he doesn't know of any either. :)
But you don't ever your license to use React. Bonus: Many people think the BSD license contains an implicit patent grant, which might well cover you even if the explicit patent grant is revoked. Again, if there are any patents to license.
