At its Uber Elevate conference today, the ride-hail company unveiled a prototype of its next big bet: an electric air taxi that it plans to launch some trial runs as early as 2020 and have full rollouts in Los Angeles and Dallas in five years.

Yet as futuristic as it sounds, the Uber Air project remains — at this point — still in its conceptual phase. Uber, for one, acknowledges in its white paper (written in October 2016) that it has a way to go and that events like this week’s Elevate conference, where it will convene innovators alongside regulators, are steps forward.

As such — and as is often the case with Uber — there are bound to be a number of massive political and policy hurdles in a plan that attempts to change cities’ transportation infrastructure. While others like the Larry Page–backed autonomous taxi company Kitty Hawk are making fast advances in the air taxi space, much of the logistical work of reshaping air travel in cities has only just begun.

At its most basic, Uber Air is a flying taxi that looks a lot like a drone. The prototype concept revealed on Tuesday holds four riders per vehicle and operates in a carpool style (which theoretically keeps prices down). A short concept video on its website details the potential hailing process: A rider books the Uber Air inside the app, heads to a building rooftop that has an Uber skyport, and scans into the facility using the app. Once there, the rider is transported to the nearest skyport to their endpoint and arranges “last mile” transport to their final destination.

Lost in Tuesday’s announcement are details…