In the magical future where self-driving cars will be able to replace 100% of what a driver does 100% of the time, what barrier to entry will protect Uber from competition? What stops someone from leasing a few dozen vehicles, and opening up their NotUber self-driving taxi service?
Especially in a world where Google Maps has already intermediated the ridesharing services. NotUber just needs to integrate with gmaps to instantly get ridership without spending billions in incentives to build their own two-sided marketplace.
When that happens, any Uber employees still holding equity are going to take a bath. They will be holding onto shares likely worth less than what they paid in taxes to get them.
Nothing will stop them, and the company to replace Uber won't own the cars. They'll simply make technology that empowers self-driving car owners to earn money with their car while they're sitting at work.
Small barriers to entry -
Cost of purchasing said vehicles
Cost of developing a Uber=style app
Even past this, the industry will never be highly profitable in the long run because of competition from people who do get past this
A completely different business model where they suddenly own tons of depreciating capital assets. Or are they going to franchise out the car ownership and keep relying on people to not realize they're losing money?