How I see SQL databases evolving over the next 10 years:
1. integrate an off the shelf OLAP engine
forward OLAP queries to it
deal with continued issues keeping the two datasets in sync
2. rebase OLTP and OLAP engines to use a unified storage layer
storage layer supports both page-aligned row-oriented files and column-oriented files and remote files
still have data and semantic inconsistencies due to running two engines
3. merge the engines
policy to automatically archive old records to a compressed column-oriented file format
option to move archived record files to remote object storage, fetch on demand
queries seamlessly integrate data from freshly updated records and archived records
only noticeable difference is queries for very old records seem to take a few seconds longer to get the results back