No, going from 1xN^2 to 2xN^2 to 3xN^2 and each further stacked layer from there on is still going to be a very major challenge (getting rid of heat being a ver

No, going from 1xN^2 to 2xN^2 to 3xN^2 and each further stacked layer from there on is still going to be a very major challenge (getting rid of heat being a very major physical challenge for a start). We're already 32 x N^2 for flash packages, but with stacked dies. For flash heat is much easier to manage as only a small part of the die is active at any one time. Stacking memory on top of a cpu core is also common practice in mobile SoCs (though still mostly package-on-package). Going to N^3 from todays M x N^2 is squarely (cubedly? ;)) in the realm of science fiction, there's a lot of space for improvement here.