Here it is :
For starters, there will be a kind of surprise, during the end credits are played. It is the first time that we do something along those lines, but there’s a surprise at the end of the game. When the end credits are played, then the Nintendo 3DS, please do not turn and be vigilant all the time. “
So, the surprise is "this leads to Kingdom Hearts III", why announce it on 3DS if it won't be on Wii U?