Why don't they use biometrics on the door handle? So you register, say, up to six thumb prints with the car and only those thumb prints can open the car. Same as unlocking your iPhone.
One possible future I guess, but finger print readers struggle with grease and the outside of a car is a dirty place covered in road film. Likely as not you'd not get in.
The next thing is likely to be using your mobile device as a key. The tech is there now,
so just another ten years and the car manufacturers will stop using a vulnerable security system and replace it with something more secure.