I just don't think RE4 is a very telling example because the GameCube came out in 2001 while RE4 came out in 2005. Had it come out earlier on, I think it would have moved boatloads of systems, but there's no way to ever know that. As it is, it came along so late that anybody that had any inclination to own a GameCube had probably already picked one up, indeed likely for a first-party game.