Mellor writes that Gartner projects a:
dramatic drop in average SSD prices, from around $0.84/GB in 2014 to an anticipated $0.10/GB in 2021. Disk drive price erosion is happening at what looks like a slower rate, from around $0.085/GB in 2014 to $0.001 or so in 2021.
Projections from Gartner and others are driven by the manufacturers' claims as to when they will deliver technological advances. Historically, these have been beloved of the good Doctor Pangloss, leading to similar optimism from the market analysts. Which is to say that I'm skeptical that the Kryder rate for either SSD or HDD over the next few years will be over 20%.