It would be wonderful if hard drives could store hundreds of petabytes of data without a change in the size of disks. However, such changes would means corresponding exponential improvements in processors to clock data in and out, memory bandwidths and networks. It seems to me that the limitations we currently experience are all tied to one another.
Perhaps the first major breakthrough should be computing technology to break the current speed barriers. A speed up of an order or magnitude (e.g. 30GHz or faster CPUs) will be the foundation for being able to process and move data much faster. But these have to appear at the same time massive storage appears.