I think you're definitely right that Facebook stands to lose the most.
And, I also agree that most businesses will be willing to pay less of a premium for FB ads after this change. But, even for the businesses that adapt their spend accordingly, their final marketing budget will be smaller, and therefore, their net income/profit from ads.
And, I also agree that most businesses will be willing to pay less of a premium for FB ads after this change. But, even for the businesses that adapt their spend accordingly, their final marketing budget will be smaller, and therefore, their net income/profit from ads.