Then learn and dream and plan, but most of all dare to set sail, or the stars shall not be yours.
Many exciting options are available for an extended mission.
One approach for the extended mission is to repeat many of the observations taken during the nominal mission with different geometries and instruments. Perhaps Cassini will discover new moons of Saturn, or a strange magnetic field anomaly that deserves further study. The Voyager spacecraft, for example, are still operating and collecting data on the outer solar system and the solar wind twenty years after launch. We expect that Cassini will have the same success in extended lifetime as the Voyager and Pioneer spacecraft. However, there are all sorts of more outlandish opportunities for Cassini after its nominal mission ends.