Specifically, this will involve a big lurch toward end-to-end encryption, which will be the backbone of newly interoperable messaging services WhatsApp, Messenger, and Instagram Direct Messages.
But Zuckerberg, having been accused of a spectacular failure of leadership over Cambridge Analytica, is convinced that this is the right way forward for his company.
Namely, it will make it much harder to detect the spread of hideous videos like that of the New Zealand mosque shootings last week, which has drawn international condemnation.
Here, Facebook says it has removed 1.5 million copies of the footage, with both its algorithms and moderators creaking under the pressure of its virality.
Here, only the sender and receiver of a message can view its content, making it impossible for Facebook or law enforcement to detect.
Facebook has already taken steps to limit the number of people a WhatsApp message can be forwarded to, seeking to stem the spread of toxic content.
It has led some to question whether Zuckerberg has an ulterior motive for his privacy vision: to absolve himself of responsibility for moderating harmful content on his platform at a time when regulators are talking about leveling huge fines on tech firms over the issue.
Concerns were also raised by Ben Horowitz, the cofounder of the influential Silicon Valley venture-capital firm Andreessen Horowitz.