Positives:
Gearing suited for the actual speeds we do - hopefully improving mpg
Less accidents (apparently, not sure how many are caused by high speed vs inappropriate speed)
Less cost for manufacturers (safety based) and buyers (tyres etc)
Negatives:
Doesn’t tackle the issue of people driving inappropriately for the conditions.
This won’t be the only technological advancement; I’d expect geo-fencing and driver monitoring to show up aswell. I don’t have an issue with geo around schools or hospitals etc, but max 60 on a dry, summer’s evening with no other traffic around?