Platter drives have been artificially held high for the past few years... and it will burn them unless they start budging on capacity and price, as SSDs will continue to drop.
With 5TB and 6TB drives finally making it out into the consumer space, platter drive pricing may finally start dropping, but will it be too little too late? Will there be enough of a market now in the consumer space to support the larger drives? I suspect the average user has plenty of storage already - perhaps to the point of full porn saturation - but more seriously... how much drive space does Grandma need for her cat pictures and baby videos? 2TB is probably more than enough, and within the year, she'll be able to save all that to a 2TB SSD that boots her e-mail/web browsing machine in an eyeblink.
Of course, the platter drive makers have brought on this trouble themselves... like the DRAM price gouging back in 1994 (The Sumitomo explosion supposedly endangered epoxy resin supplies, prices of RAM tripled overnight), platter drive makers have taken the same opportunity to create a scarcity to drive prices up and keep them up. They also delayed higher capacity platter drives, giving the SSD makers an opportunity to catch up. They can't keep this up and stay in business.