"The passcode screen that Federighi got on that first iPhone X said “Your passcode is required to enable Face ID.” This is the same screen that would come up on existing iPhones after a device has been restarted — or simply after several hours have passed without authenticating through the lock screen. This is a security precaution introduced with Touch ID that will clearly carry onward with Face ID." - via
Eközben Samsungéknál: https://www.youtube.com/watch?v=fXU9FUfyGCI