In the subtitled version of the recent trailer of KH:DDD, Yen Sid mentions something about getting a 'Key of Sleep' and if they return, Sora and Riku will be Masters (I assume they must return with the key). It just occurred to me, could this Key have anything to do with awaking Ventus? What are your thoughts?

possibly, or it could be a term that yen sid is using to refer to something other than an actualy "key" that way its kept a secret as to what he may need them to return with

I don't think it has anything to do with awakening Ventus. But is somewhat related to the word "dream" in the title of the game.

aqua is gonna wake ventus right so i think you'll need her 1st but you might be right that would be kool if after they wake ventus

x-blade

I think it might have something to do with them looking for the hidden data within Sora. In that, I think it'll have to do with reviving all of those in torment.

 

Remember how Ansem in Blank Points said, "He could open the right door, and save all those people whose lives I managed to ruin."

 

I think the Key of Sleep is the Key to that Door. All the tormented people are "asleep", after all.

Yen Sid lied, there is no key of sleep. He just sent them on a wild goose chase because he was bored.

The Key to sleep proably awaken's one's hidden power. Though it'll be cool if it did wake up Roxas, Xion, Namine, and Ven.

Yen Sid lied, there is no key of sleep. He just sent them on a wild goose chase because he was bored.

 

Obviously the truth lol. Actually it might be, if he wanted to just wanted to test their hearts.

Maybe to awaken the memories in Sora that where mentioned in Re:Coded

Maybe Aqua alone can't awaken ventus so in order to release Ventus's sleeping heart since none of them have a Keyblade of people's hearts they need to get the Key of sleep first then find aqua and then find ventus while awakening ventus with the key of sleep.

Perhaps hypothetical key to finding Aqua, becuase she is the key to waking up Ven from his sleep after all.