I don't get this. Why would you think you would have any problems? Every car ALWAYS comes with a method to get in that does not require any cellular or internet connection. The S and X come with regular key fobs. The 3 and Y come with that RFID card that can be held up against a sensor on the door pillar.I think I’m going to be in deep do-do. Should lock car in rural areas ( temptation esp. with a Tesla) but maybe can’t,? I’m on a wildlife refuge quire often , in the middle of no where and hills block cell reception. Might be 16 miles before I can get cell.
What I described with using the phone app over the internet connection is just an extra secondary way to access the car.