10 years ago, it was inconceivable that taxi cabs would not be necessary. Today, not so much.

In the case of air travel, RJs have the highest CASM. It is inefficient. It is only done to add frequency to smaller cities. That whole 'regional feed is necessary' line is bovine excrement - the hubs can be fed with mainline aircraft flying to outstations with a bit less daily frequency than RJs currently provide.

Let's examine DEN-TUS. When I lived in TUS a few years ago, it was 5 RJs (RJ only) per day service. I just pulled up next Monday's schedule. It's 4 Rjs and one A319.
This could easily go to 4 A319s per day, losing one flight per day, and still have more seats available than is currently offered. Or 3 A320s/737s per day.

In addition to increased travel demand, there are fewer new pilots entering the industry than are leaving it (retiring/medical). If you think that the highest cost, most inefficient portion of air travel will survive the dual pressures of increased travel demand and decreased supply (of pilots), that's awesome. I'm sure there are some taxi cab drivers who are also expecting their niche to recover. Times change. Living in the past is a poor life strategy.