Mark Zuckerberg has a plan to fix Facebook, and all it will take is completely rebuilding Facebook, Messenger, and Instagram.

The Facebook CEO published a lengthy post laying out "our vision and principles around building a privacy-focused messaging and social networking platform." The post explains more about the company's plans to merge WhatsApp, Messenger, and Instagram's messaging features, as well as a broader shift to encrypted and ephemeral content across its services.

"As I think about the future of the internet, I believe a privacy-focused communications platform will become even more important than today's open platforms," Zuckerberg writes, noting that private messaging and disappearing Stories are already very popular.

Zuckerberg identifies several idea he says will guide the new, "privacy-focused platform," including: private interactions, encryption, reducing permanence, safety, interoperability, and secure data storage. "Over the next few years, we plan to rebuild more of our services around these ideas. The decisions we'll face along the way will mean taking positions on important issues concerning the future of the internet," Zuckerberg says.

Notably, the CEO has already spoken about one major change that will come from incorporating these ideas: combining the messaging infrastructure of WhatsApp, Messenger, and Instagram so that users can message each other between apps even if they don't have an account on each one.

The idea, which was first reported in earlier this year and has already received pushback from some European regulators, would also extend to SMS on Android. "We plan to start by making it possible for you to send messages to your contacts using any of our services, and then to extend that interoperability to SMS too," Zuckerberg says.

He explains:

This could also improve convenience in many experiences where people use Facebook or Instagram as their social network and WhatsApp as their preferred messaging service. For example, lots of people selling items on Marketplace list their phone number so people can message them about buying it. That's not ideal, because you're giving strangers your phone number. With interoperability, you'd be able to use WhatsApp to receive messages sent to your Facebook account without sharing your phone number -- and the buyer wouldn't have to worry about whether you prefer to be messaged on one network or the other.

You can imagine many simple experiences like this -- a person discovers a business on Instagram and easily transitions to their preferred messaging app for secure payments and customer support; another person wants to catch up with a friend and can send them a message that goes to their preferred app without having to think about where that person prefers to be reached; or you simply post a story from your day across both Facebook and Instagram and can get all the replies from your friends in one place.

Zuckerberg also writes at length about increasing end-to-end encryption and ephemerality across its services.

"I believe there's an opportunity to set a new standard for private communication platforms -- where content automatically expires or is archived over time. Stories already expire after 24 hours unless you archive them, and that gives people the comfort to share more naturally. This philosophy could be extended to all private content."

You can read Zuckerberg's full post here.