Brian Bailey writes :
Flash memory has very quickly risen from being an obscure memory type to perhaps becoming the dominant memory type for many devices, including music players, cell phones, tablets and now increasingly servers and mainstream PCs. But flash memory does not scale quite as well as the more traditional DRAM that it is replacing. It is thought that DRAM can scale down to 1nm whereas we are already hitting some problems with the scaling of the floating gate in NAND flash. It is not thought that planar NAND can go below 10nm which is only a couple of processes steps away from where we are today.
3D NAND flash is coming - [Link]