What was in room 11 in "The God Complex"?

What was in room 11? What was the Doctor's Greatest Fear?

The room was dark and it played the tardis sound and Matt Smith said "Of Course, who else?" (Could it be the dream master, or the master, or the time lords of old?)

Also on a side note, "That which holds an image of an angel becomes itself an angel"

Wouldn't the angels in the room themselves become REAL weeping angels?