It seems Samsung is finally suffering the same effects in its SSDs as it has in its other products, other companies have caught up and are able to perform nearly as well for a lot less money...Looks like the Samsung 970 is to the 960 what the Galaxy S9 is to the S8.
Samsung responds to the criticism/competition with price cuts across the board. That's a pretty hefty cut to the 512GB and 1TB 970 Pro.
when sales fall, the inevitable price cuts surface to stimulate sales
price cuts are standard in the semiconductor sector which has been studied heavily in economics
the street calls it price rot
Generational improvements become smaller and smaller as a technology improves, giving consumers less reason to upgrade with each iteration. That leads to price drops to stimulate sales as mentioned, which causes more of the potential market to buy in, which in turn, leads to fewer people in need of an upgrade the next generation. Eventually the market is simply saturated, and prices have fallen as far as they can to maintain profitability, and everyone who was going to buy, already has.
Then you either need to open up new markets, or substantially improve the technology.