I agree with Appaccelerator1, the HDD as we know it will go the way of the dinosaur. It will hang around for quite some time, just like the 1.44" diskettes. But at some point the "mega-cache" will be cheaper than the mechanical parts, and even hybrids will become extinct. Although with a closed Helium case for hd's you might extend the hybrids a few more years.
But it's not only price and performance that matter, it's also physical size. With smartphones, pads and laptops taking over the consumer market, and PC's as we know them are phased out; size will matter! The traditional HD will probably never get smaller, but SSDs will.
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