This can only happen if someone develops a storage technology that is simultaneously the lowest cost, lowest latency, highest bandwidth, lowest MTBF, lowest pow

This can only happen if someone develops a storage technology that is simultaneously the lowest cost, lowest latency, highest bandwidth, lowest MTBF, lowest power, smallest footprint, and includes every extra feature (ECC, encryption, etc). Until that unicorn exists, engineers need to select a storage technology that meets requirements for the use case at hand. If these requirements result in a mix of storage technologies, then at some point it's likely to require moving data from one storage device to another. HPE believes (believed?) in your vision and made a lot of noise about "The Machine", a memristor-based system which incorporated a lot of ideas around the sorts of hardware and software architecture changes that would come from a radical change in the underlying storage technology.