For what it's worth, we're coming off of the bottom of a bust cycle in the NAND flash space.

The OP's graphs basically capture the NAND market from the previous boom through the current bust. So from that specific perspective, SSD prices have been dropping like a rock. The only catch with that window is that it fails to capture the cyclical nature of the market - and thus fails to illustrate how SSD prices go back up.

In practice, SSD prices have hit their lowest point. They are going to rebound here until the next bust in 2-3 years.