There is a new alternative to the foldable phone already. Nubia has unveiled the Alpha, a device with a screen that curves along a wide watch-like form factor. This display is 4 inches long, and operates using the Snapdragon 2100 wearables processor.
https://www.notebookcheck.net/Nubia-Alpha-the-flexible-wrist-phone-unveiled-at-MWC.410921.0.html