Like the politicians who kept the Vietnam War going long after victory was impossible, they don't understand sunk costs. They are all in at this point. No prosecutor of a case this big will accept the embarrassment of merely dropping the charges. They have to win, so this will go to court.
There's more than one way to win. They could declare that they "settled for undisclosed terms", declare victory, and walk away.
Many of the people Obama has appointed to top positions in the DoJ are ex RIAA/MPAA folks.