I actually speculated that there would be a Siege of Stormwind raid tier in WoD, considering all the parallels they were throwing back to the First War. It would've been cool to see the AU Iron Horde actually succeed in going through the Dark Portal and assaulting Stormwind, forcing the Alliance and Horde to band together and free it from the Iron Horde's grasp. And besides, we had one raid in Orgrimmar... so, why not Stormwind?
Obviously that didn't happen, so I'm all for a COT of the original Siege of Stormwind.