We hope to see HDD and SSD combinations or future hybrid HDDs that would support writecaching, particularly for notebook and especially ultra-thin notebook computers.
Writecaching could allow the hard disk drive to stay in a lower power non-spinning state for longer periods of time, extending battery life for the notebook computer.
Writecaching would store data to be written on the HDD in flash memory initially until enough data was in the flash cache to do an efficient write to the HDD disks.
Perhaps the biggest gain may be in dual storage computers where a flash memory device is used for storing operating systems, software and frequently accessed content (and maybe even for writecaching) while a hard disk drive provides much less expensive mass storage of user data.