Uber is losing billions and their drivers are making peanuts. That sounds sustainable.
They are basically biding their time until driverless cars take off it seems.
So, at best, they become a 40-billion dollar driver/rider match-making algorithm and a pretty CRUD app. Unless Uber itself is working on autonomous driving technology. It's so easy for drivers and riders to switch between ridesharing apps (e.g., ever see an Uber driver that also has a Lyft sticker on their car? I have, many times), I don't see how any of them can solidify a competitive advantage of sorts long-term.