[dogma1138]

In the US many cars already have a microphone for AAA type services, some cars will automatically dial home/911 if they've been in a car accident where the air bags have been deployed.

As for the data not leaving the dashcam it won't at first because internet connectivity is still spotty and expensive, eventually it will probably stream it live to you insurer which will perform some analysis on it to see how you drive in order to define your premiums, so if you speed you get to pay more. It won't surprise me if insurers don't already have access to some telemetry from cars (e.g. the one which is downloaded during routine checkups) that can be used to extrapolate your driving behavior for example how often you break suddenly/emergency break, most modern cars come with accelerometers today to ensure that air-bags deploy properly even when the is hit from the rear or the side that data is probably stored in the control box.