An NPC named Robin has been found. WoWhead, asite that scours the game code for new additions, picked up three instances of the tribute in a recent update for the Warlords of Draenor beta build - a male human, a female human, and a blue genie.
This model has been used before as a boss in a dungeon, but the idea is that this version of the model will most likely transform into other Robin Williams' characters.
The thumbnail spoils one character, but I don't want to spoil anymore in case this is real so just watch the video if you are interested. There are some real interesting characters and the possibility of... DLC for some old favorites.