Mark, I think you are correct in that the question, "Who you gonna get to do the dirty work when all the slaves are free" is essential to the meaning of Passion Play. You hit the nail on the head when you said that the question could be interpreted two ways. Joni is the queen of dualism, so it is hard to say which question she is really asking - probably both! This is at least the third song with a reference to slaves in it ("a good slave loves the good book...", "where the wealth is made, the slaves will be taken.") This must be a question that she ponders quite often. Will empire succeed empire ad infinitum, with the powerful preying on the weaker ones, until mankind is no more? Or will a radical transformation occur, when there will be no more slaves? The second scenario is possible, with the level of technology we have reached, if it were shared with all. Much meaningless grunt work could be eliminated, freeing everyone to live fuller lives. But Joni is more aware! than most of the "darkness in men's eyes" that seems to kill any chance of that ever occurring.
Thanks to all for giving me food for thought. I was totally lost on this song before this discussion. Ruth in Richmond NP: 'The Job That Ate My Brain' The Ramones