A few years ago, there was talk of producing chips with three dimensional stacks of NAND cells (for example, http://www.semi.org/en/node/38361?id=sgurow0811 ). Has there has been any movement on this front? Every article I can find on the subject is a year old or more. This strikes me as the ideal way around the limits of individual NAND cell size, with an obvious proviso that drastically new manufacturing techniques would need to be perfected before this limit is hit.
If it can be commercially produced, that would definitely set us up for a while for flash (CPUs would be thermally limited); though interestingly, not really that long!
If each layer was 50 nm high, and you built the chip up to an unrealistic 1 centimeter high (eg, a 1 cm^3 chip instead of 1 cm^2), chosen because that would pretty easily fill a 2.5" drive, that would give you:
(1 centimeter) / (50 nanometers) = 200,000 times today's capacity.
Which is only only 18 doublings, or 36 years more of Moore's Law (assuming the pessimistic 24 month end), or roughly the gap between a Commodore 64 and a decent laptop today. Some people still working in the industry have gone through a larger increase. I've gone through a 1000 fold myself, and I'm only 25.
There are sure to be a whole bunch more we can do to get more capacity, but it's pretty mind blowing to think that the theoretical limits to storage are within our lifetimes on an exponential scale. So as much as Moore's law hasn't failed us yet, it certainly will at some point (probably in the form of the doublings themselves exponentially taking longer and longer).
They're only within our lifetimes if you require the devices to be the size of modern day silicon chips. There's nothing preventing us from building bigger devices - I mean, my laptop and smartphone's SSDs already essentially act as caches for much larger remote storage and compute hardware.
And given that nature has managed to cram this amazing sentient device into a space the size of our skull, using a pretty inefficient design process, I'd say the problem will be not the quantity of the building blocks, but how they're organized :)
If we were willing to accept SSDs being as unreliable as human memory, we could increase capacities by an order of magnitude with current technology. In fact, if SSD controller design weren't so tricky, someone would have taken advantage of this already to build a pretty decent enterprise-scale caching system.
