Buses have failed for a variety of reasons. Rail and BRT (bus with dedicated lane) are good and should be greatly expanded, but they only help with connecting major areas. We need to stop looking at Asian mega cities as an example. It just won't work here. Those super dense cities are designed for walking + public transit. The "last mile" problem in those cities are solved by walking because they're super dense enough that you can get to public transit easily by walking less than a mile. And also don't look at NYC or any old east coast city as an example. Those were designed before the car. Most people in the US live in places that were designed for the car.
Rail + BRT along major routes is part of the solution. But in the past, it hasn't worked well because of the "last mile" issue, which is more like the "last few miles" issue in the typical American suburban design. If someone has to still have a car to drive the few miles from their home to the park-and-ride, that doesn't do anything to fix the local road congestion issue. When they get on the train, it helps with freeway traffic, but does nothing for the local traffic. And the "last few miles" is too far to walk. And again, buses/shuttles have failed to fix this for a lot of reasons.
When ride-share was introduced, some thought that this was the solution. If someone depends on ride-share to get to places, that certainly helps reduce parking requirements. But, the traffic on the roads doesn't change, and may even increase due to idling ride-share cars waiting for rides. Uber Pool tries to help with this, but it's just not enough.
With the rise of electric micromobility (e-scooters and e-bikes), we finally have something that can fix this "last few miles" issue. But it will require a big step from the government and society as well. We have to be willing to sacrifice a lane in all the local roads. The current bike lanes are simply not extensive enough, not wide enough, and not safe enough. The only way to achieve true effectiveness for e-micromobility is to dedicate an entire lane of roads to them. It's a radical idea that would get a lot of opposition. People already upset with traffic don't want to lose a lane to make it worse. That can only be countered with a critical mass of people who own an e-microbility solution (e-scooter or e-bike).
Is it ever going to happen? Maybe if there's a city brave enough to try it and show it can work. But true support and infrastructure for e-bikes and e-scooters is the only way to get real density in the typical suburban sprawl layout without a disastrous increase in traffic and parking shortage.