I've thought about all this before. I see it being possible to make it work how newer cars work, but being a lot of work. Requiring chips and sensors for a key/keyfob, locking out grinding the starter, and also making the button turn the car off, or into strictly auxiliary. Making it even more difficult for myself would be how it would interact with my remote start. Would pressing the button turn the car off, do nothing, or work as intended? And if it doesn't work, how would one make it work?
So many possibilities.
And **** if you go through all that trouble you may as well give the car range-sensitive door locks. If you get close, unlocked, if you get far enough away, locked... again, like a new car.