UniKey - Your Phone is Now Your Key (unikey.com)

If someone steals your phone then they have access to everything that the phone unlocks. Not practical.

Unless if there is some kind of a way to deactivate the phone when it's stolen. Problem with that though is, what if you don't notice it when the phone goes missing..? Giving the person that stole it ample time to get access to whatever it is they were targeting.