One of the key points during the Bethesda E3 presser was that the über classic The Elder Scrolls V: Skyrim will be released for PlayStation 4 and Xbox One in a Special Edition version. It will also be released for PC, and Bethesda has a nice surprise in store for those who previously bought everything for the game already, and confirms: "If you own #Skyrim and all its add-ons or own Legendary Edition on Steam, you'll get a free upgrade to Skyrim Special Edition on Oct 28 #BE3."
So there you have it. If you have the game and have bought all the extras, you'll get the Special Edition for free. This only applies to Steam and no other PC services, and not the console versions either.