There are lots of people in research looking at incorporating SSDs into the storage hierarchy in various ways. Not sure how much of this is going to be productized in the short term, but I wouldn't be surprised to see, say, a new release of a commercial DBMS that can use SSDs for some of the buffer cache.<p><i>Also, the current situation with flash memory being expensive won't last long, and moving to pure solid-state storage is still better than this 3-tier architecture.</i><p>For scan-intensive workloads (e.g. datawarehousing), I'd expect to see magnetic disks continue to be used for quite  some time. Buying a petabyte of SSD would be <i>expensive</i>.