It seems like Facebook is merging the chat systems for Instagram and Messenger on the Instagram app. It was noticed on both iOS and Android devices that Instagram's app showed a new screen with an update option. The screen had the message “There’s a New Way to Message on Instagram”. A list of features was also displayed including a new look for the chats, more emoji reactions, swipe to reply, and chat with friends who use Facebook.
If you choose the option to update, the icon of DM on the top right corner of Instagram's interface will be replaced by the Facebook Messenger logo. The chats will also change color from blue to purple as you scroll. However, the update will still not enable the option of using Instagram to message friends who use Facebook.
It is still evident that Facebook is working on integrating its three big popular apps, Messenger, Instagram, and WhatsApp to connect people using different platforms via cross-messaging. The entire system will be end-to-end encrypted, according to CEO Mark Zuckerberg. Furthermore, integrating the apps would potentially allow Facebook to become a competitor of iMessage by Apple.