If a car company charged more to simply turn on a feature that ought to exist, like driving in a blizzard, then I would never buy a car from them. ever. I only have one life to lose and it's not going at the hands of some scummy company that intentionally holds back software it can install in an instant so it can nickle and dime me.
Upgrades generally not just(or possibly even) safety software, will have an assigned value of the developer hours assigned to creating and maintaining upgrades and will be built into the cost of cars. Unlike 4 wheel drive, which legitimately needs to be more expensive having much more hardware, software releases can leverage pre existing APIs and hardware interfaces.
If we assume that either all cars have the software priced in, a "good actor" would allow you to pay less for "blizzard navigation software" if you lived in S. California.
At this point, Tesla is so new that they will make it as attractive as possible and push all of their updates for free. I also have a high degree of trust, at least relative to other auto companies, in Tesla. One would imagine GM, or another less scrupulous company would try to do something like this if they were the front runners.
edit: Point taken though. I am also not keen on some of the other car and boat manufacturers producing identical engines, and then having you "pay" to unlock more horepower.
