I'd really like Harmonix to find a way to plug a proper electric (or acoustic with an internal pickup) guitar to a console. Then they could redevelop Rock Band to actually teach real cords and strumming patterns. Not only could they truly make a killing but they'd be teaching folks something a lot more useful. Hell, sell the game for whatever, and then you could sell individual songs as DLCs as you get around to them and get the proper licenses.
Watch, someone's bound to respond and tell me that somebody else has done this like 10 years ago and I just hadn't heard about it.