Here are two competing theories of how the coming transportation revolution could impact American life.

One possibility is that easy mobility—driverless cars, on-demand deliveries, and the like—will dull the pains of suburban life. The long commute, the wasted driving time, the difficulty of running out for a carton of milk—the inconvenience and expense of the subdivision will be melted away by hot new technology. Milk by drone, what a concept!

Another is that easy mobility produces greater advantages in the city. Carless living is better than ever. NIMBY battles don’t happen because parking and congestion aren’t problems. Wasted auto infrastructure, like lots and curbside parking and garages, is converted towards better uses like housing and restaurants. Maybe a central highway, once evidence of a city’s essential unpleasantness, becomes a park.

Those two futures might both exist, but is it possible that the technology could push Americans away from the suburban status quo? Or it is the opposite? Will freedom from driving allow us to live closer together, or permit us to live further away? Consider the question a loose societal analogy to Clayton Christiensen’s business dichotomy of disruptive versus sustaining innovation. Does the transportation revolution sustain American sprawl or disrupt it?

Two op-eds published Thursday make the case one way and the other for the driverless car and the American settlement. In Bloomberg View, the economist Tyler Cowen argues that new technology—not just cars, but also virtual reality and the Internet of Things—has advantages that favor the suburbs. In the Wall Street Journal, Uber CEO Travis Kalanick posits that new technology will create “a more livable and less congested” city.

Cohen’s argument is in some ways convincing. He’s right that driverless cars and on-demand delivery could bring perks to the suburbs—a commute spent reading a book, say, or the quick purchase of that one-percent pint—that have traditionally belonged to urbanites. It’s also true that new technologies, like a smart home heating system, are more readily installed in the modern, spacious suburban home than the older urban apartment. (Ask a New Yorker if she’s ever had a garbage disposal.)

But how much weight do these inventions put on the scale? The services that Cowen awaits at his Virginia home will still be subject to the same low-density distribution costs that have restrained taxis from roaming suburban streets, and currently limit Amazon from offering two-hour delivery beyond cities. Even with drones, greater distances will keep delivery marginally less efficient, slower and more expensive.

Futurists have been peddling some iteration of the “death of distance” theory—the idea that tech is making proximity irrelevant—since the invention of the telephone. Yet people are still drawn to work, eat and socialize in company. Videoconferencing hasn’t killed the office; online universities haven’t discouraged kids from shipping off to college.

Kalanick, meanwhile, is at the helm of a company that has infiltrated virtually every possible mode of mobility: long-distance trucking, package delivery, food delivery, and of course, personal travel in shared and/or autonomous cars. He and his peers have striking visions for what a city freed from private automobile ownership might be capable of.

Lyft President John Zimmer envisioned such a city in a post on Medium earlier this month. Imagine a world (in your best movie trailer voice), “A world where we need less parking — where streets can be narrowed and sidewalks widened. It’s a world where we can construct new housing and small businesses on parking lots across the country — or turn them into green spaces and parks. That’s a world built around people, not cars.”

We at Slate are frankly intrigued by the possibility that autonomous vehicles might have such an effect, and we’ll be dedicating a Futurography segment to ownership next month that will have a cool video on this future city.

But Kalanick makes a great point in his piece: autonomous transportation is actually the less important component in creating “a city that lives and breathes more easily.” The more important concept is… sharing. Not the bullshit low-paid menial labor that has long characterized the sharing economy, but actual sharing, where two people get in the same car together.

The most radical future is one where self-driving cars are shared, both on a single trip and between trips. A slightly less radical future is one in which individuals are willing to use a car someone else has just used, but prefer to ride alone.

But what if most people want their own autonomous car, all the time—a car in which you can leave your suitcase while you have lunch, where there is no camera watching because nobody uses it but you, where the air freshener and the radio station are the ones you chose? That, as Clive Thompson pointed out in Mother Jones, would hardly produce the de-congested, parkified city of the future. That’s more of a Cowen future than a Kalanick future. That’s a future basically recognizable as our present, albeit with higher car payments, more traffic, and more time to watch TV on the way to work.

Some companies, like Uber and Lyft, are interested in selling rides. They will want to keep their fleets as small as possible, because cars cost their companies money, and rides produce it. A model where people share rides would be generally preferable, because a high customer-to-inventory ratio would be better. A denser population will be a more efficient market for them.

But what about the companies that build autonomous cars? They will want to sell as many as possible. Whether that’s to individual owners or to collectivized fleets, well, who knows? But either way, sharing isn’t good for their business model. When have we ever shared something when it has been feasible for each of us to have one of our own?

Regulation could be one way to tip the scale towards sharing or away from it; towards the urban-utopia model and away from the suburban pattern of today. But another factor will simply be consumer choice: How much is it worth to have a car of one’s own, an extra space that belongs to you, that smells like you? How much is it worth to ride across town alone, in silence? How much does it cost us if that’s what everyone wants?