Re: The price is astronomical, but..
http://www.cdrinfo.com/Sections/News/Print.aspx?NewsId=42245
Hard drives can go past 15 TB using shingles, bit-patterned media, hamr, two dimensional magnetic recording, etc. - and maybe several at the same time. But at the rate SSDs are growing, they will never catch up. This 15.36 TB is before generational improvements to V-NAND that will include 100+ layers (thousands?) and shrinking back to 1X nm. They will still have high endurance when they shrink because they will be able to massively over-provision using the layers.
By the time hard drives manage to lumber on to 100 terabytes (in a large form factor than SSDs), there may be post-NAND/Crossbar/XPoint available. Ultimately, holographic storage will blow past what hard drives can store.
http://www.nature.com/news/2009/090124/full/news.2009.54.html
https://en.wikipedia.org/wiki/Areal_density_(computer_storage)#Research