There is a quick pan outwards and it is revealed that there are hundreds upon hundreds of keyblades sticking out of the ground. It strongly resembles a graveyard. There are for pathes carved out, which have a striking resemblence to the crossroads from Chain of Memories. The crossroads proved as paths between light, dark, twilight (as DiZ said) and dawn (as Riku said). Each character in the trailer comes from a different path, indicating a different state of heart. It is clear the crossroads will play an important part in KH3.
~From http://kingdomhearts.rpgplanet.gamespy.com

Also this is something i thought for myself but ill share it..well alright i think the 3 people that you see...well i think they are took the different paths..one took the dark path...one took the light path...and one took the twilight path...you can tell how there keyblades look like on what path they took.