Uber is unsustainable, both the core business and for the drivers. They've survived this long because they were able to dance around regulations and take advantage of drivers. But things are changing: insurance companies are onto drivers and governments are onto the businesses. All of this is going to drive up costs. They are gambling on surviving longer than traditional taxi companies can.

Economics are not in their favor. There's a reason taxi service is expensive. It's hard enough to provide cost-effective public transportation, much less private transport.

Once driverless cars hit the streets, then the calculus changes a bit. But that's when the competition will really begin. What's more likely is Google/Amazon will create (or acquire) a driving service broker that will automatically hail for you from whatever service will offer the ride cheapest (and probably won't even take a commission).