Fumito Ueda, director of The Last Guardian, seems to be teasing a new game from developer genDesign posting a piece of concept art on their official website. The creator did the same long before the reveal of The Last Guardian, with an image showing Trico's chains and some feathers.
The art shows a beam of light with a dove flying above a girl on top of a staircase. On the right, there's also a big clenched fist, which maybe could indicate some sort of King Kong-like story, but that is just speculation.
You can view the concept art below: