I've long hoped for Uber to roll out on-demand door-to-door UberPool with 14 passenger vans. They could match riders to drivers and find the optimal route in real time, with pricing and travel time falling between public transit and UberX, all in the footprint of a F-150.
No need to wait for autonomy. They have (had?) such a service in Cairo, but unlicensed jitney vans were already common there. They never launched it elsewhere.
If yes, perhaps cities with fewer cars can skip the taxi step and go straight to smart buses.