Don't be sure about that. Remember that the Thai floods setback HDD prices and made them more expensive for years; they still haven't returned to the pre-flood trendline last I checked. With SSDs dropping, that might deter much more investment into HDDs (and with less demand from HDDs in the first place, there will be fewer of the economies of scale & learning curves that drove previous HDD price decreases - and vice versa for SSDs!).
Today on newegg it's about $0.03/gb.
I only point this out because I assume you misunderstood what was said about the trend line, if you had another purpose for pointing this out which I am missing I would be interested in knowing it.
I'm not able to find an up to date enough trendline to agree or disagree with his statement.
They have. I remember buying 2TB drives a year before (2010). I paid about $200 each. Last year (2014), I bought 4TB drives for $130 each. That's about 3x improvement over 4 years, right?
https://en.wikipedia.org/wiki/File:Diagram_of_Hard_Disk_Driv...