Wow. Economics education is worse than I thought. Even people who think they've had a course in economics don't know what they're talking about.
First, what makes you think the MBP has a high level of price elasticity? Mac users tend to be LESS price sensitive than other computer buyers.
Second, even if there is some price elasticity (I'm sure there's some), what makes you think that the volume would increase enough to make up for the loss in profit?
Third, let's say there IS price elasticity and it's enough to more than make up for the drop in margin. Why isn't Apple doing that today? After all, they probably know more about their costs and margins than you do.
Bottom line is that Apple believes that the current price optimizes profit - so lowering price would NOT provide an increase in profits. So your price elasticity argument is nothing more than wishful thinking.