That dire warning comes from SanDisk's CEO Eli Harari. The capacity of flash chips has doubled 19 times in 14 years to 64 billion bits, currently. But Harari says they're "running out of electrons."
The short story is that the number of electrons crammed inside of flash storage now makes them less accurate as they get older—they "start to smear"—and that Harari thinks they can only double chip capacity two more times. When they go from the current 64-billion-bit chip to the 256-billion-bit (32GB) one, that's the end.
There might be some salvation in stacking the layers, but it's not ready for prime time yet. Check out more of the grisly bits over there: [Bits]