At this point in time, I think it's wise to avoid laying costly new tracks with the dawn of driverless cars on the horizon.
In fact, this is a perfect use case for driverless cars. The problem with trains everywhere is the wasted time not on the train and the million stops along the way.
It gives us exactingly detailed information on what journeys people need. The dataset will be immensely valuable in allowing the companies that sit on them to first start doing quasi-bus services:
Order a bunch of minibuses. During peak hours, offer an option: Wait for the next dedicated car to be free, or ride share with quicker availability and a discount. Limit detours strictly - there'll be plenty of "Follow road X and pick up 6 people on the way to station Y" type stretches that will make people happy (little time lost; feels efficient if there's not lots of turning off).
Then you can see them partnering with bus providers to dynamically fill in during peak hours, or even bidding for bus franchises and proposing contract changes that would allow for more dynamic, demand-based scheduling.
Ultimately this can feed into planning train type services - companies offering these type of drive share will be able to e.g. let people order "end to end" journeys of the type "pick me up at address 1, get me to address 2" where they show journey options that include rail when it makes sense. The key beying that if they do so, they will know the entire desired journey, and would be able to offer insight into the most efficient interchange locations or other changes to train services would be most desirable.
The raving reviews you'd get the first times people order a car and are told instantly "your car is already waiting right outside your door" would be rather interesting.
Get in, and your favorite radio station or music is playing.
And for colder climates: Your car is already pre-heated. I remember too many winter mornings during winter in Norway when even ensuring our car would actually start in the morning was an annoyance (even with a garage, space heaters in the garage or motor heaters is sometimes necessary).
Yes they will; the magic trains you're thinking of are called streetcars. And, with the oddities in oil and the difficulties of maintaining suburbia, we'll be moving back to dense streetcar suburbs soon enough.