All the suggestions for new areas to explore in-game in the middle of the generation's run time sounds like stuff that would save everyone a lot of grief if it was just hard-coded into the game to be accessed through a mystery gift item. Most likely the mode of transport to get there would be present before you download it, so the game would at least have predetermined space set aside to download that area, so I can't imagine that they would create events where completely new information is getting written on to your card/downloaded copy.