Maybe not, but if the speed limit is increased to 80, soon they'll be driving 85.
Probably see a slight increase in folks driving 85.
Most people are creatures of habit and have a comfort zone for speed already. They won't change their driving habits . I already see people driving 85-90 mph out there no matter the posted speed limit. They will continue driving like that.
The traffic fatalities / 100,000 people actually decreased for several years after the National 55 MPH was repealed in 1995. Here is a link to the Stats.
Vehicles are being made safer and safer each year so that definitely contributes to a reduction in fatalities regardless of the speeds.
https://en.wikipedia.org/wiki/Motor_vehicle_fatality_rate_in_U.S._by_year