If you lose A smart key, there's no problem. You just need one working key to program additional keys into the system (and delete old keys, if necessary). However, if you lose ALL the keys, you must replace the PCM at a cost of ~$600 (parts only, no labor or keys included).

Even for programmable or non-electronic keys, the thief may just be wasting his time. Half of the keys cut on the usual duplicate metal-cutters don't work anyway...they may fit in the slot, but usually have metal burrs and take an endless amount of grinding down before they will actually turn. In addition, some dealerships ask for proof of ownership before actually giving you the key.