Vehicle Emissions: Necessary or Outdated?

Emissions testing may be on the way out. In the 1970s when air pollution was at its peak, Congress passed the “Clean Air Act” to combat the growing problem of hydrocarbons, carbon monoxide, nitrogen oxides and particle emissions in the air.  The EPA had full control over regulation of transportation emissions, and those standards have had a profound effect on the air quality of today.
Vehicle companies have taken proactive and innovative steps to deal with emissions since the1980s, and newer models have significantly reduced the amount of air pollution they emit by up to 99%. And with the inclusion of OBD2, the onboard diagnostic system that triggers the “check engine” light, vehicle owners can fix a problem quickly with little repercussions to the environment.
In a recent study by the National Bureau of Economic Research^[1], it was concluded that emissions testing on newer vehicles had “no economically significant effect on air pollution”, and according to the EPA^[2], the next logical step towards cleaner air rests on the focus of carbon pollution from fossil fuels. If this is the case, how much longer will emmissions testing be needed for our vehicles, and will the focus shift to other forms of power?