I think it'll sell well, but I just don't think people will actually stick around and play it for any length of time. It's scope is huge, people like having objectives and when you put them in a giant open world where they can do anything, they get bored fairly quickly. Not sure what all 'quests' the game will have at this point, but if the game's quest system isn't as endless as the universe, it's going to run short on content.