The self-driving car is very much going to project that sinks Uber. It's an enterprise so far outside their core business, with such a sheer volume of money required to bring to fruition, and they're just not going to get there. Moreover, it's not at all clear that their financials support being able to back a project like this if it doesn't bring quick and immediate success.
Google are probably the current leaders in this field. And to their credit, there's a logical value there - Google's business is, essentially, AI - which is what the problem boils down to (and integrates nicely with the rest of their search business - object identification, categorization etc.).
When investors start wanting to cash out, Uber is going to wind up sliced and diced and a lot less valuable then it looked on paper due to projects like this which they can't possibly fulfill.