I can't independently verify this, but some astute viewer recently reported that ALL of the footage of SE in the new WDW planning video is quite old and does not contain the wand and "Epcot" signage on the exterior. Perhaps the removal of these items is the "change" to which the OP refers...
Epcot wasn't even around when we first went. No question, the ball is very recognizable. I still think other rides come more quickly to most people's minds, but that's hard to back up. If for instance you were to do the Family Feud type thing with "Disney World" as the category, my guess is the top few things would be Space Mountain, Cinderella's Castle and the monorail. Would be fun to find out though!