I posted this last February...
"With or without self-driving cars, vehicle-to-vehicle communications will become required on all vehicles, bicycles and pedestrians under the ruse of public safety. Preying on people's fears and fascinations, the media with political backing will over-publicize horrific vehicular and pedestrian collisions and carnage in order to sway public opinion in favor of vehicle-to-vehicle communications. This will at first be a separate transponder unit, but will quickly be integrated into personal tracking and surveillance units, a.k.a smartphones. This data will then be used measure and collect road-use taxes which will be renamed "infrastructure investment shares". As concerns over accuracy and health come to the fore, the strength of the radio signals will be reduced, necessitating larger, more optimally shaped antennas spurring the return to separate units which eventually develop into mandatory helmets for cyclists, pedestrians and passenger car occupants. Certain, popular lightweight materials for clothing and vehicle construction will also be outlawed due to radio-wave reflection and interference. Meanwhile, as a result of the "collision and carnage" campaign "human error" is percieved as the weak link in the system and the push for self-driving vehicles revives and this time succeeds. Adapting existing e-bike technology and electric shifting is a cake-walk, and thanks to the "Bicycle Stability Act" traditional two-wheeled bicycles are phased out in favor of tricycles and quadra-cycles. True, two-wheeled bicycles will be required to employ either a segway-like balance system, or a large, heavy-mass, spinning gyroscopic stabilization unit. The result will be an expensive, complex, heavy, heavily taxed, autonomous, self-driving personal recreational and mobility unit the average bicyclist will neither recognize, enjoy, nor be able to afford. And contemporary parts or standarizations will no longer be part of that equation."