"I'm expecting an explosion of these new light vehicle body types in the coming decades, as global trends of cheap electric drive + batteries, increasing urban congestion, and less car-oriented urban planning trends converge"

Don't motorcycles already serve that purpose? Its already the chief form of personal transportation in most of the Earth's population.

The problem I see with all the concepts you posted is that they have all the drawbacks of a car and a motorcycle. They would fare as well as a motorcycle in a crash, and have almost the same footprint as a small car. Also, a motorcycle will handle much better than a trike with narrow tracks and short wheelbase at higher speeds.

Then, there are electric assist bicycle. They have two main problems that small motorcycles/scooters don't suffer from. A 350lb scooter/motorcycle is much harder to steal than a 50lb electric bicycle. I own a rather expensive electric assist mountain bike that I don't feel comfortable parking it out of my sight. You can't travel on the highway with electric bicycle unlike motorcycles.

I think you might be underestimating the size of a modern car -- they're huge!

By small car I meant Smart ForTwo, or Fiat 500. These not-a-car trikes/quads have comparable footprint to these cars. Which isn't small enough to fit in-between 2 lanes.

Sure, but those are exceptions to the modern car size, and the median car size on the street is far bigger than that. If everyone would switch to Fiat 500 sized cars, that would be an amazing start.