WhatsApp, Facebook, Instagram to merge soon

At the moment over 1 billion people around the world use WhatsApp Messenger for texting and sending videos to friends but it seems how all of that works is about to change.
However, all the 3 apps will remain stand-alone apps but they would be able to communicate with each other easily.
Whatsapp Merge With Facebook And Instagram (What It Means)
What this simply means is that a Facebook user could communicate directly with someone who only has a WhatsApp account or Instagram account. The development of this plan has already started and we should be seeing it by the end of 2019 or next year.
This will bring together three of the world’s largest messaging networks – Facebook, Instagram And Whatsapp bringing about 2.9 Billion people together.
However, my major concern here is how it puts our privacy at risk. WhatsApp already has end to end encryption, Facebook has an optional way to activate it while Instagram doesn’t have the feature at all.
Hopefully, before it’s released we would see considerable updates in that direction.