Mercedes-Benz new subscription model: increase performance for only $1,200/year

Being able to change the parameters of a cars performance via a radio signal sounds extremely troubling to me. Will a malicious actor with an SDR figure out how to push an update that, say, disables the brakes above 60mph?

Also plausible, how long until government demands this sort of control to enforce safer traffic? Example: you drive past, say, a high tech school zone sign that temporarily, automatically limits your speed to a max speed of 20mph.

Is this plausible?