Still have to carry at least insurance card, driver's license, health insurance card, car registration (well, I never leave mine in the car). I don't see that changing anytime soon.
Car keys are interesting- hmm, some cars will allow the phone to do lots of stuff (mine doesn't, though). Haven't seen Android home locks yet, but there are those with combination locks.
But what happens when you carry no credit cards, no debit card, and no cash, and your phone crashes, is dropped or submerged and ruined, suddenly has zero battery, or is missing? You would be stuck "away" and with absolutely no way to pay for or buy anything! Oh- we submit our fingerprints to the state and then not only can all our movements be tracked with phones and plate readers and cameras, but now everything we touch can be tracked too! Maybe I am too old and conservative.