You never know, they did eat up the cost of the new iPad's Retina Display and its insane (almost twice the previous capacity) battery. Those were the two most expensive components on a 16GB iPad and the cost of production went up around 50% according to the iSuppli breakdown, yet the selling price stayed at 499$.
Don't forget that Apple usually has a lower margin at the beginning of a design cycle than at its end, and I'm sure the MBP will be no exception. Even if they only put regular hard drive in standard configurations, the Retina Display alone will make the hardware cost/selling price ratio better than previously.
You also have to consider that SSD prices went down since they introduced them in Macs, you can now buy them individually for around 1$/GB, and Apple's price is obviously way lower than that since not only would they place a very large order, but
they now actually own a flash memory firm, so they would only pay the production cost. I'm guessing it would cost them maybe 100-150$ for 256GB of SSD, which is less than the estimated price of the upcoming (and pretty much confirmed) 15" Retina Display.
Profit margins for current Mac laptops are estimated at 28%. The current MBP probably has a higher profit margin than the MBA, so let's assume it has around 35% margin, meaning around 1,170$ of costs to make a 1800$ 15" MBP. Let's say now it would be 100$ more for the Retina Display, 150$ more for 256GB of SSD, 15$ less for the removal of the SuperDrive and 40$ less for the removal of the 500GB hard drive. Let's also add 20$ for a ~30% bigger battery. That would make the production cost go up to 1,385$ (23% margin) and up only 18% from the previous MBP. Like I said, the new iPad's cost went up almost 50%, so it's not completely inimaginable to see that happen.