That's the way these things work though. Start-up moves in, offers good rates because they have the VC money to burn. The early adopters do well (like drilling for oil), then after several years reality sets in. The legacy employer no longer exists, in fact, there are no competitors except one or two global technology companies. Finally, cars drive themselves.

And what happens when Uber continues to lower the rates Uber drivers earn at? Eventually taxis will look like a better job again.

That's a meaningless hypothetical. Why would Uber do that? They have every incentive to make sure that drivers are getting paid as much as possible and that riders have the cheapest prices possible, they literally have hundreds of people working on finding the equilibrium.

Once you become the de facto platform and you move from a start-up to a multinational public company, there's no longer a need to look after the contractors. There's added pressure to milk those contractors for all they've got. The contractors are easily replaceable and will live under constant threat of upcoming automation.

No. Uber will always have the incentive to keep drivers happy, as they are competing with every other job. If another position values their time more they will move there.

On the topic of self driving cars, full saturation is at least a couple of decades away.