The feature was already rumored earlier this year, but it was finally confirmed at yesterday's f8 developer event. It is unclear how the interoperability would exactly work, as WhatsApp relies solely on phone numbers, while Instagram and Messenger require users to create their own accounts. Thus, to what "phone number" would WhatsApp user send a message to when wanting to contact a person who is only in Messenger.
Company didn't give a clear timeline for the change, but it wont happen soon - it seems that the next year is most likely timeline for the roll out.
Written by: Petteri Pyyny @ 1 May 2019 14:38