A quick note to say that Oracle Database 18c is now available on Oracle Cloud and Engineered Systems.
Please read Dom Giles overview post of 18c at: https://blogs.oracle.com/database/oracle-database-18c-:-now-available-on-the-oracle-cloud-and-oracle-engineered-systems
Dom covers some of the key features introduced or improved in this release.
In particular, there are some interesting improvements that I anticipate the Autonomous Database Services to use heavily under the covers. These include the Zero Impact Patching for Grid Infrastructure, Online PDB relocate – including connection redirection, improvements to patching Java in the database (OJVM) and more.
The 18c New Features Guide is a great place to start getting more detail.