Components haven't dropped? I can buy a 1 TB SSD from Samsung that is faster than the SSD's Apple use and much cheaper than what Apple charges. RAM is cheap. CPU is cheap since it's an outdated CPU replaced by Haswell several months ago.
You know, you are comparing apples and oranges. What I wrote was not about possible price drops for current rMBPs, but the yet-to-be-released Haswell machines (and I assume that's what the OP meant too). You are also comparing retail third party HDD prices to Apple OEM upgrade prices, neither of which have much to do with rMBP margins.
Some things to consider, when making estimates of the Haswell rMBPs price:
Competing products are priced similarily.
RAM prices are up
Haswell SKUs are pricier than Ivy Bridge, compare the prices of
Ivy Bridge vs.
Haswell mobile parts.
On the other hand NAND and
rare earth metal prices are down.
Only the screen could be expensive but the costs should be lower now than 1 year ago.
Better yields improved the availability of Retina displays, but there is no information, whether the screen in Haswell rMBPs will be the same as in Ivy Bridge machines. And it's still a hugely expensive part, likely the most expensive single part of the whole rMBP.
Price drops of other old parts (CPU, GPU, chipset, etc.) would be relevant only if the parts used in the new rMBP were the same as one year ago, but they of course are not. New parts -> new prices.
Apple is quite known for having higher margins than the competition if you look at iPhones. And it's not R&D costs since Samsung has 3 times more R&D costs than Apple.
Huge margins in iPhone have not much to do with rMBP margins. There were several estimates of the 15" rMPB margins floating around back when it was introduced, and they found its margins to be even lower than those of other Apple laptops, which are also not much higher than in the industry generally.
About the R&D, Apple works quite closely with, for example, Intel and display manufacturers, who invest heavily in R&D, which Apple in it's turn then pays in component prices. The Retina displays are a good example of this.
Comparing Apple R&D investments to Samsungs is also comparing apples to oranges. Samsungs range of products is something quite different from that of Apple, ranging from chemicals to semiconductors, and everything in between. It's a company that develops tech and parts for not only it's own consumer products, but for other companies too. It's actually one of the companies that has made many of Apples ICs and displays, so historically Apple has paid a part of Samsungs R&D in component prices. This is to change of course, as Apple is shifting the production of both ICs and displays to other manufacturers.