I wouldn't go so far as to predict a long term upward trend, but prices are not going to continue their historic exponential drop. Like I said, cost reduction achieved by shrinking the node size (i.e. Moore's Law) was the main enabler for the exponential drop, but that trend has ended. This is common knowledge for anyone who follows the semiconductor industry, if you want data look it up yourself. Prices will surely still drop, but only incrementally. In particular, the PPU of SSDs will not be competitive with HDDs for the foreseeable future.