An article in the Economist on "tuk-tuks" - three-wheel vehicles common in a number of countries. In the rural Philippines car ownership is still only for the well-off, and taxis ... well, if you're well-off enough to afford a taxi, you can afford a car or get a ride from someone who does have one. On the other hand, tricycles are everywhere, a motorcycle with two seats beneath an awning in the back, spewing exhaust and drowning conversations, while guaranteeing that the clouds of dust never settle.
With hindsight we know why people want 4-wheelers, among other things stability at high speeds, but the idea of an inexpensive 3-wheeler persists. On the motorcycle end there's the 3-wheel "Can-Am" BRP Spyder, and the now-defunct Aptera Motors plan for a mass-market 3-wheel car. Now I've never seen an actual Aptera, though the Henry Ford [Museum] in Dearborn long had a rear-wheel drive 3-wheel vehicle from [pardon my memory] 1903 on display.
...not all niche configurations disappear...
Standard histories will note the shift from engines under the driver to the front-engine, rear-drive layout (nodding to the 1891 Systeme Panhard). But in the early post-WWII era 3-wheelers were also prominent in Japan; as late as 1960, they comprised the majority of vehicles made (and in Japan trucks dominated until 1968). Thereafter output fell, and then plummeted, but in 1963 roughly 1 million were in use. Several of today's manufacturers got their start making such vehicles, particularly Toyo Kogyo (today's Mazda), Daihatsu, and the Mizushima plant of what is now Mitsubishi Motors. Now Mitsubishi exited in 1962, shifting output to (small) 4-wheel trucks; Daihatsu made such vehicles until 1972, and Mazda until 1974.
Stability was an issue, and that became important as roads became better so that speeds rose and maneuverability less critical. (In Japan's case, licensing exemptions helped, lasting until 1965, but the industry was already dying.) Four wheels helped too as vehicles themselves became larger. But 3-wheelers persist, in forklifts and tractors. Though most have two wheels in front, they are close together to allow a short turning radius.
Ironically, at higher speeds modern electronic stability systems offset the tendency of trikes to turn over, braking selectively, and paring back the throttle. That however is for operations on standard roads. At lower speeds and off roads, stability remains problematic: farming is the most dangerous occupation in the US that employees large numbers, and one source of danger is overturning equipment. So 3-wheelers persist more widely than people realize, and their potential remains. Outside of commercial applications, however, there's no evidence that they will ever be more than recreational products: at first opportunity, most people move from smaller to larger cars, and the cost differential of using only 3 wheels surely can't offset that preference.
The larger story remains that the variety of potential vehicle configurations is large, and most have been produced at one or another time. Some persist in niches – 3 wheelers, rear- and mid-engine vehicles. Not all niche configurations disappear: today front-wheel drive accounts for most vehicles around the world.
