If your business is dependent on Facebook you need a plan for if all that traffic goes to 0. It's happened to the news media, it's happened to games on Facebook, it will happen again.
I'd like to add that it didn't happen to news media (yet). I help with SEO for one middle-sized news media, and FB traffic is up to 25%, not more. I have read that others have bigger numbers, though.
Like the scorpion, it is in its nature.