WhatsApp is reportedly working on usernames, which will allow its users to choose unique names for their accounts and communicate with each other without the need to exchange phone numbers.
WABetaInfo has spotted the new feature in the latest beta version 18.104.22.168 of WhatsApp for Android. As a rule, new WhatsApp features first appear in the Android app, and then are rolled out to the iOS app.
Currently, you need to know a contact's phone number to message them. With the ability to choose a username, WhatsApp users will be able to add another layer of privacy to their accounts. Instead of relying solely on phone numbers to identify contacts, they will be able to search for and add people by their usernames.
Since this feature is still in development and not yet visible, it's too early to talk about the timing of its release. This feature should become available with one of the updates of the messenger, which WhatsApp will probably announce officially.