Blizzard's Battle.net offers a simplistic but free communication system for guilds and groups, but many players opt for other tools like Discord when it comes to communication. This could change in the near future, though, if information leaked by MMO Champion (via PC GamesN) is to be believed.
The forum contains a portion of the code datamined after the last update of the service that refers to new features such as groups and the option to appear offline instead of busy or away. There's also a lot of images of the new group icons and avatars that Battle.net will probably offer to customise your profile too.
Would you leave other communication systems if Blizzard updates Battle.net?