I think the major unanswered question is how reliable do we think the machine is? 50%? 100%? I think the most interesting scenario is one where we are convinced that the machine actually predicts the future and always predicts correctly, so I'll continue with that assumption in mind.

From one point of view, we have no reason not to take both boxes, since we can't alter the machine's prediction now, it's already happened. I think however that this undermines my premise. Choosing both boxes only makes sense if we don't actually believe the machine predicts the future.

One would be tempted to say "alright, then I will choose only box B, as the machine will have predicted that and I will get lots of money. If I were to choose both boxes, the machine would have predicted that too, and I would get much less money.

My argument is that both answers are wrong in a sneaky way: assuming an actual perfect predictor, my answer is box B only. However, the important part here is that this will not be, in fact, a choice. The result was already determined ahead of time, so I really only had that one option.