I think Uber's business model relies on self-driving cars. They're paying subsidies now to build a brand -- the name "Uber" has become synonymous with "pull out your cell phone and call for a ride" -- that will be very valuable once self-driving taxis become a commodity (which will happen shortly after their introduction).
Uber is not a bet on who can build the most profitable taxi company now -- it's a bet on a brand in an industry that will rapidly commoditize. Given that literally everything else Uber does has been replicated by at least one team at every hackathon I've been to in the last decade, there is very little sustained advantage from technology.
The auto industry is at a crossroads: you have new upstarts like Tesla that are very obviously planning to convert to a transit-as-a-service model. The "old" auto industry (basically everyone that makes cars and is not Tesla) is still struggling to adapt to a more "continuous development" model like Tesla. Tesla's engineering process is far simpler -- an electric car replaces the complex internal combustion drivetrain (an engine block that requires separate air, water, oil and gasoline systems, plus the transmission) with a far simpler electric engine.
The electric system in a Tesla is actually far simpler than your average car: the sensor package in a modern internal combustion engine is an incredibly complex piece of engineering. This gives them a huge cost advantage over existing automakers -- if Tesla is providing transit as a service directly to customers AND making/maintaining the vehicles themselves, that displaces a lot of revenue (auto sales/maintenance to companies like Uber).
I think Uber will eventually merge with an auto manufacturer (and likely keep the Uber branding since it's likely to be the most valuable part of the company). They already have realized that Tesla is their biggest competition; and I think that the autonomous driving deal with Ford is simply testing the waters for a future acquisition.
15 years from now, most people will likely have 3 or 4 choices of how to get somewhere by car: Uber, Tesla, Lyft and likely a mix of local / regional companies. Brand value is powerful; and I guarantee you that at the end of this, the Uber brand will be worth more than what they've put into it.