David Hayter posted this interesting old video (recorded after MGS4 on 2009) about his prediction on the next MGS game would be Raiden as the main character. Also, it is funny to see all the main voice actors were in this video : David Hayter/Snake, Jennifer Hale/Naomi, Paul Eiding/Colonel, Christopher Randolph/Octacon & Quinton Flynn/Raiden.
