@MomentoMori It's locked because it isn't released yet. They can't have an E3 Trailer when E3 is two weeks away.
@Everyonewonderingaboutthesecrettab
Its new Multiplayer info, of this I am sure. Two reasons:
1. The Days Site's secret tab released info on the characters in multiplayer you had to unlock, Mickey, Sora, Xion, Riku, etc.
2. When they officially announced the NA release(Not the date)they mentioned there being extra features for multiplayer, it wouldn't surprise me is those updates were:
a. A Vanitas unlockable(Highly unlikely, but I must play as him!)
b. An Eraqus unlockable(Again, wishful thinking)
c. A Xehanort unlockable(Once more, highly unlikely)
d. A Survival Mode, like, they just release rounds of enemies endlessly until you die. It was in Brawl, I'd enjoy it here.
e. Extra Arenas
f. Extra enemies/bosses