100 years is ambitious only if you want to remove all of the cars. There are plenty of milestones that can be attained fairly quickly :
Smaller cars. Less energy, materials, etc. Safer for other road users (you don’t get hit on your vital organs, better vision for the driver and everyone else since pedestrians can easily see over the car).
Less car use is available now, if we just empower the alternatives (make bike usage safe, make public transport good enough)
No more cars in cities. Bikes + trains mostly do the job, you can rent a car if you leave the city, or park it at the outskirts.
Even smaller cities used to be liveable without a car. This could be brought back, but that’s probably a tough hill to climb.
100 years is ambitious only if you want to remove all of the cars. There are plenty of milestones that can be attained fairly quickly :