While there will always be incentive to simplify these systems due to cost pressure (especially as ADAS becomes a mainstream, high-volume technology), I believe that the most effective systems will combine multiple sensor types -- such as vision plus radar. And I think that when it comes to saving lives, we want the most effective systems. Over 1 million people die annually worldwide from automobile accidents.
The European funding project MOSARIM (MOre Safety for All by Radar Interference Mitigation) started in January 2010 with the main objectives to investigate possible automotive radar interference mechanisms by both simulation and real-world road-tests and assess possible countermeasure and mitigation techniques in general guidelines and recommendations.
Picture this: A roadway 3 lanes wide, every vehicle has radar. What prevents inter-vehicle interference? Do all the adjacent vehicles have time-domain sync with each other to prevent registering the pulse reflection from the vehicle in the next lane?