Comment by layla5alive

Yes, in 2D, but NAND has been using layers for a while. We call HBM interposers 2.5D. 3D breakthrough would be pretty easy but for those pesky problems like power delivery and cooling. (/s)

But give that time (e.g. microfluidics) - something interesting is that it would be extra hard to use all layers at once, but NN might be a good fit, imagining that computation will be sparse (subsets activating simultaneously)...