Today maybe but the price per GB is also falling at a rate far faster than traditional magnetic storage.  The writing is on the wall.  Still HDD are probably not going away completely for a decade, but they are going to get pushed further and further into a niche over the next few years.

Flash already dominates small form factor devices (smartphones, tablets, consumer electronics, etc).  At one time HDD held in all those areas.  There were HDD in compact flash format, early mp3 players used small hdd, some video cameras recorded to DVD or HDD.  You can't find HDD based products in those areas any more.  

The next HDD market to be killed off is probably the laptop.  The form factor is smaller (2.5" vs 3.5") and the prices are higher ($0.10 to $0.20).  So it is an easier fight and the marginal cost increase isn't much relative to whole system cost.  Flash has the advantages of lower power consumption, less noise, higher reliability when it comes to shock.   The relentless march of Moores law will kill that market off too.

At the high end RAID using enterprise SSD is being considered more seriously in applications where IOPS are critical (like database servers).  A 2U server can mount 24 2.5" SSDs which is just an insane storage density


Of course hard drive companies aren't stupid, their strongest area is high capacity low performance applications (backups, nearline storage, archiving, etc) so HDD are going to get much bigger to stay competitive.   So it is win-win all around.  Still if I was WD I would be looking to buy a flash company.