Alright, I've got no historical sales data to back this up but:
From the first paragraph of the article in the first post of this thread:
***Quote***
The traditional hard drive market is down with many computers, tablets, and other electronic devices that need storage moving to faster and more rugged flash-based offerings. That means that sales of traditional HDDs are faltering due to increased demand on the market for tablets like the iPad that are taking sales from the notebooks and netbooks.
***Quote***
Since when has an iPad been a device designed to replace notebooks and netbooks? My understanding of the iPad is that it is designed to fill a market niche, and right now, there's no competition. It should be (mostly) increasing the overall demand for mass storage needs.
Anyway, I completely agree with most of the posts above stating traditional HDD's are not going to go away. Cost/GB is getting better every quarter (a nickel per GB is freakin awesome).
In addition, to say SSDs are going to replace traditional HDD's is like saying a new sports car is going to make pickup trucks obsolete. Sure, they can both take you from point A to point B, but every similarity between the two ends there.
Bottom line: SSD's and HDD's are two completely different products aimed towards two completely different uses.
Maybe, in 5-25 years (thinking more along the lines of about a decade, and it all depends on where the development money is put) SSD's cost/GB will move low enough to compete with traditional HDD's. The whole point is SSD's are about 5 years old (I'm guessing here), and we're just seeing the 3rd generation controllers for SSD's. Traditional HDD's have been around for about 30 years (another guesstimate), and the technology has been refined a lot. Whether or not SSD's replace HDD's in the future depends on how much further Spindle technology can be taken, and at what cost, compared to how far SSD technology can be taken, and at what cost.