I suppose, if it's a German system, it probably won't just give a warning, it'll kill the ignition and then say "For you, ze drive is over"!
More seriously, I know there's a huge amunt of work in this area going on. This is very sophisticated, but there are already regulations being drafted for "lane departure warning systems" - the sorts of things that shake the steering wheel or driver's seat when you drift out of your lane. On the face of it, a good thing, and another reason why newer cars are likely to be safer in the future (or, if the scamera partnerships are still around, another reason to justify
their existence)!
However, we also have to look further than the good idea. It would be SO easy to then get the ECU to log the number of times it had been necessary to "wake you up". It could log the frequency and duration of each dozing-off episode and store them for the crash investigators...
Now that, in itself, mightn't be a bad thing, but once you start convicting people on the strength of it, the system would have to be damned reliable! As a society, we might also have to accept increased intervention and surveilance of our actions.