Square Enix revealed a special trailer for "Kingdom Hearts III" during the D23 Japan Expo and it was expected that the trailer would then be released to the general public. The latter info proved to be a hoax and to this date no word from Square Enix hints that it may be available online. 

The trailer in question does focus on a few new details regarding the game. As stated in a report from Gematsu, there is a dialogue exchange shown in the trailer between a young Xehanort and a young Eraqus. As revealed in the portable "Kingdom Hearts" games, both were students of Ansem the Wise and were both Master Keyblade wielders.

A report from Design & Trend has a breakdown of the actual dialogue and for the most part Eraqus and Xehanort discuss the details of the ancient Keyblade Wars. Xehanort tells Eraqus the "truth" in which it is already decided that during the end days the darkness will win and take over the light.

Xehanort also mentions "The Lost Masters" but the dialogue appears to be purposely cut to remove the explanation as to who these Masters are and if they are still alive. The trailer cuts from Xehanort's mention of them to a discussion regarding the aforementioned "truth."

The report cites that it appears very clear that either Sora or Eraqus plan on re-writing the ending that Xehanort speaks of. By doing so they may be able to prevent the darkness from consuming the universe and allow the light to take over for good. It is hinted that this may be achieved solely through Kingdom Hearts.

Gematsu also points out that the trailer revealed new forms of Heartless and Nobody, although it did not showcase any new levels or worlds. It is heavily speculated that worlds based on Disney's "Tangled" or "Frozen" might make an appearance in the game.

"Kingdom Hearts III" has no official release window, although it is expected to release by 2016.