Skyborne Race Overview: Racials and Customization
On the Classic WoW subreddit, user Odin_69 showcased an interaction with another player. The chat window shows both players speaking Darnassian. By selecting that particular language (which all Skyborne currently have access to), players can effectively speak each other's languages across enemy lines.
That said, it's up in the air as to whether this is intentional or if it is just a bug stemming from the fact that all Skyborne start out at the same place. Blizzard has previously been strongly against blurring the lines between Alliance and Horde too much, and while many players are praising this ability (thinking in terms of roleplay and worldbuilding flavor), it would go against the game mechanics that have been established up until this point.
For now, though, cross-faction talking does exist - if you're playing one of the Elf classes, next time you're out in the world and see a Skyborne in the opposing faction, try starting up a conversation to see for yourself.
