Yeah. Not actually that big of a deal that they make it out to be... Just like the Power of the Cell.
There are plenty of ways to side-step the issue of storage speeds, we have been dealing with it for decades after all.
Compression, Mesh/Texture Streaming, Longer Load Times into larger DRAM buffers, Procedural Generation... List goes on.
NAND certainly has it's advantages when leveraged right, especially in asset streaming and load times, but usually game engines are engineered to deal with the lowest common denominator... And that is mechanical storage.
Next gen I would assume that developers will still need to keep in mind for mechanical storage on console (External) and PC.
We will seen a great benefit for PC gamers as well who have been used SSD for quit long time. Probably there will some setting on game option for PC gamer to choose between fast loading or normal loading time.