I think there's precedent with the OnStar system in other cars, and there has anecdotally been evidence of various systems being operable by some kind of admin terminal.

I think "summon mode" is actually a great demonstration of how you can remotely access and do some form of piloting the car without a driver. There's also the disabling of features remotely on resale, and probably other examples.

Even then you can always install an update that allows remote control.