Yes i think there could be a chance i too have had both Magic Kingdom hours extended and spectromagic show put on for 6th Sept, but Epcot that week has also extended its hours, means we'll be in there until midnight for EMH!
I suggest check Walt disney's official site the week before you go for the most uptodate hours. The only thing we will miss and still is the case is the Nemo musical, there are no shows the whole time we are there!