It’s been more than a year since Facebook announced it plans to merge the Instagram and Messenger Chats into one platform. This will bring “a New Way to Message on Instagram”.
In the new update, the regular DM icon in the top right of Instagram is replaced with the Facebook Messenger icon. The new update will allow you to message your friends both on Facebook as well as on Instagram. What this essentially means is that the DMs will now be as colorful as the Messenger. The DMs will have more emoji reactions, swipe-to-reply, and other features present in the Messenger.
In US, Instagram users on both iOS and Android have started receiving an update. With this update, you no longer have to keep switching between these two apps. Facebook has future plans to merge its Whatsapp platform too.
via - GMSarena