ToF camera sensor can be used to measure distance and volume, as well as for object scanning, indoor navigation, obstacle avoidance, gesture recognition, object tracking, and reactive altimeters. Data from the sensor can also help with 3D imaging and improving augmented reality (AR) experiences. In phones, ToF camera sensors will likely be used for 3D photography, AR, and in particular portrait mode.
Theoretically, ToF cameras can better blur photo backgrounds in portrait mode. We say "theoretically" because the process still requires software magic, and in the end, it's up to a company to decide how it applies the data that the ToF camera collects.
ToF cameras can also assist in low-light situations - since the sensor uses infrared light to pick up "distance-to-subject", it could help smartphones focus even in darkness.