Quit Facebook Day is going to be called a failure because of less than massive turnout. Quit Facebook Day is actually successful for the very thing it intended to do: bring light to the Facebook privacy issue.
The idea was that Facebook was being disingenuous with privacy, saying that they wanted to allow users greater control over their privacy, while all the while operating on a business model that does better with less privacy controls. More information in your profile allows advertisers to target you with direct advertising. A better environment for target marketing makes bigger revenue for Facebook.
The obvious conflict of interest here has left Facebook scrambling to create a better PR image while only modestly revamping privacy controls.
Quit Facebook Day shouldn't be judged by the number of Facebook users that quit yesterday compared to the number that stayed on, but rather by whether or not it actually helped create awareness of the double standard provided by Facebook.