i think i understand it.. you're basically talking about different amounts of friction between tire and road surface.
even rudimentary ABS's already do that.. so we've pretty much got the stopping figured out.
the vehicle stability control system in my inexpensive car already uses vehicle speed, yaw, steering input, etc. to simply apply braking on one side or the other to correct for over/understeer (which is caused by human error to begin with). i could only imagine if it took control of steering itself, how much more effective that would be.
as for being able to see a roadway -- i REALLY dont trust a person.. computers can use visibile light, ir, microwave to see roads AND traffic better than we can.. not to mention GPS and INS for positioning.
you're probably right that it's probably 10+ years away from reality, but nevertheless. i think the technology already exists and i doubt ice and snow is much more a challenge than driving on wet roads...
we're also assuming the current self-driving cars can't do it already. why are we assuming that?