You can now always be safe knowing that it will start getting very difficult for a thief to steal your smartphone.
There will be special software on your phone that will watch how you use the phone and thus can build a portrait of your behaviour. From this the phone will be able to detect if a thief uses it because they will probably use it in a different way. The phone then locks itself.
It's a special type of logging software that monitors everything done and can build a profile.