Cable cars are a very energy efficient and environmentally friendly means are mass transit. They would likely be cheaper to install across the country and cheaper to maintain then other forms of transit such has bus or train. Cable cars create a more vibrant feeling for cities and are likely to generate more revenue to mass transit authorities.
Cable cars should not be used as mass transit. They are to costly and too slow, while also not being practical for most cities a to use. The city of San Francisco is the only major city that I can think of that uses cable cars and that is only used because of tradition.
I believe cable cars should have been left in place longer than they were however, we opted to dismantle them in an effort to make room for cars. I believe that was a mistake, but there's little we can do to fix it now, especially since we are so use to cars. I do not believe cable cars would make a good means of mass transit at this point.
Cable cars are far too slow to become mass transit anywhere in the United States of America. They should not even be a means of transit now, but the mountainous regions need them for steep elevation. These things are too slow to even be efficient at the slightest degree possible.
I think overall cable cars have very little play in society today, they block large sections of the road for their tracks and often move at a slow'ish pace, I think overall cable cars are nice but not a very efficient or effective way to utilize for mass transit systems.