It's not a matter of "can we do this in our lifetimes" it's "we shouldn't have gotten to this point to begin with, how do we get out of it?" The answer is "not easily" but a component of it is moving away from traditional American car culture. It's sort of like saying "I'm as leftist as anyone but I don't see how we'd move away from capitalism as an institution - too much of America's infrastructure is tied up in the private sector." You gradually move away from things and figure out alternatives over time. A good place to start is the cities themselves - they're clogged with vehicles and they don't need to be. Invest in urban public transit infrastructure and then move outwards. Will there be places that always have cars, like in the most rural parts of the country? Probably. But you tackle the problem first in places it can be solved and accept compromises over time as needed.