What's the derivative of that growth look like, though? It could be that they just have enough customers who are either locked-in or on the back-half of the adoption curve, allowing them to limp in with some growth for a few more years before it's over.
Amazon charges a premium for convenience and for the fact that there's 0-startup cost to get going with them. Why would someone every shell out the money for an enterprise 15k disk when they can buy an SSD instead?
The 15k HDDs will likely be replaced by SSDs, the 7200 ones are likely to stay for a long while yet. Their capacity is yet unmatched, the SSDs are trying to catch up with higher densities but currently the HDDs are ahead of them on the curve of size and definitely ahead on the cost per Gb.
I just recently switched my laptop to an SSD and the change is amazing but I'm not going to replace even the 1TB HDDs on my nas with equivalently sized SSDs. Both from a needs view and from a cost view.
Amazon charges a premium for convenience and for the fact that there's 0-startup cost to get going with them. Why would someone every shell out the money for an enterprise 15k disk when they can buy an SSD instead?