How is going to be 'cataclysmic' for FB? They can still serve up ads. The ads won't be as targeted as before, but they still have billions of users. Advertisers

How is going to be 'cataclysmic' for FB? They can still serve up ads. The ads won't be as targeted as before, but they still have billions of users. Advertisers will spend money on the platform. Perhaps they'll have to spend more since they can't fine-tune the ads as much.