Depends on how you measure success. Uber has yet to make a profit and they depend on VC capital to subsidize every ride. It hasn't yet established itself as a legitimate business model.
In my opinion, Uber has a legitimate software model, but it's business is not sustainable. The software, and ease of use is their selling point outside of fake deflated prices. They need to sell it to cab companies, and be the OS that runs them.
They're waiting for driverless cars to become a thing...so they can fire all of their non-employees and reap huge profits. They're playing the long game.
Full driverless cars that can go down your high street with no one in the vehicle are a way off. Uber's cash will last about 2 years at the present rate.