According to Laminar, scenery will be downloaded as required when a new flight is started. Then, when no longer needed, the items can be deleted from your device or stored for future use.
Moreover, “Going forward, we’ll be able to take updates from the Scenery Gateway, too. Every few months, Desktop users pick up some 500 to 1,000 new 3D airports from the Gateway, plus hundreds of improvements to existing scenery. Now we can bring those same ongoing improvements to Mobile as well.”
Release is currently planned for this summer.
If you’d like to read the complete announcement, see the source post via the X-Plane blog.
*Images courtesy of Laminar Research.