Google recently announced that Android will support Foldables. A number of hardware companies (e.g. Samsung, Lenovo, LG, etc.) have announced plans to explore some version of a Foldable phone. Samsung, a major Android partner, has formally introduced its foray into Foldables with the Flex Display. Google made the announcement at its latest Android Dev Summit.
A Foldable smartphone is a new form factor for developers to consider, and Google specifically called out three things its keeping in mind when supporting Foldables: screen continuity, multi-resume, and multi-display. Screen continuity means that an application can be moved from one screen to another automatically. This can take place upon an action like the folding or unfolding of a phone. Google's Android support for Foldables will push out a configuration change for the updated layout. Check out the runtime configuration change in the developer guide to learn more.
Multi-resume addresses a multiple-window situation. While Android already supports some multi-window configurations, generally only one of the windows is in a resumed state (i.e. the others are in an OnPause state). To help take full advantage of the multiple-window nature of Foldables, Google will allow manufactures to keep all apps in resumed. More details are forthcoming on this support feature.
Multi-display allows users to move an activity from one display to another. Further, when an app initially launches, the user can determine which display that app runs to. Check out Multi-display support in the docs to learn more. It appears that foldable phones are making a comeback. However, this time, the Foldables will be much smarter. Check out Google's blog post announcement to learn more, and how to test the Foldable features.