There’s a lot wrong in that summation...
Right now, there isn’t much of a plan to transition to unleaded avgas, at least not in the way most pilots think about it.
Well, the FAA doesn't have much of a plan, but the wise among us were never pinning our hopes on the FAA figuring out what science is, and how to pursue it. Better for the public purse that they've stopped trying.
The best hope, until recently, was the FAA’s Piston Aviation Fuels Initiative (PAFI), a government-sponsored program to evaluate different fuels in a consistent and rigorous way. The goal was to avoid competing standards from companies more interested in market share than technical compatibility.
That was never the goal. The FAA was quite clear that they were not trying to pick a winner, or eliminate competing standards.
PAFI’s ... moving along steadily (if excruciatingly slowly) until this summer, when the FAA stopped all testing. The press releases were vague, but essentially the problem was that none of the fuels were meeting the hoped-for standard.
PAFI might have been moving along steadily, but it was going the wrong direction; the FAA wasn't allowing the participants to do real science, applying what they learned to improving the formulations. So they were doomed to fail.
Even [if] GAMI and Swift make it to your local FBO, the distribution will be fractured and the decisions for pilots will be confusing.
That's not likely true. Both fuels plan fleet-wide acceptance by the FAA, and the eventual Swift fuel and GAMI fuel are likely to converge on intermixable options. Both Swift and GAMI have publicized information on pricing; and if licensing of blending creates MORE competition in the avgas marketplace, competitive pricing could mitigate any increase in blendstock prices.
electric airplanes are the future, at least for ... small general aviation airplanes.
That's far from clear from the physics; even light-weight batteries are heavy, and long recharging times make long cross countries problematic.
The depressing conclusion from the PAFI debacle is that there simply isn’t a drop-in replacement for 100LL, a fuel that could be used in a wide variety of airplanes without major changes to ground infrastructure or airplane performance.
That "conclusion" is not supported by the facts.
One possibility is that airplane engines will have to run on unleaded auto gas in the near future. That would solve a lot of problems with distribution and infrastructure – it’s widely available in the US
Not so fast. Most of the mogas supply contains ethanol, which is not compatible with aircraft for a number of reasons. And the pervasive effect of mandatory ethanol octane on the gasoline marketplace has made the higher-octane blendstocks unavailable.
Would you run your Cessna 310 at 50% power instead of 75% power? That’s the type of tradeoff pilots may have to confront.
There are very serious certification issues if you can't make 100% power at takeoff, and addressing those on an aircraft model-by-model basis makes that approach very, very expensive.
Cirrus introduced the SR22T model in 2010 with a lower compression turbocharged engine. It is widely assumed that one reason for the company’s design choice is to accommodate unleaded fuel if that becomes necessary.
Not sure who you believe "widely assumes" that, but they're unlikely to be engineers. The design choice was made because Continental and Cirrus were both acquired by Chinese concerns, that wanted to use their owned technologies; and Continental didn't have a more-efficient turbonormalized solution to offer. Lowering the compression ratio but delivering the same horsepower doesn't reduce the octane requirement, which doesn't have a lot to do in any case with whether the fuel is leaded or unleaded. Fuzzy thinking.
Electronic ignition, the standard in cars for many years, would be a great way to increase the number of high compression engines that could run on unleaded avgas
How? None of the existing systems retard timing to allow use of lower octane fuels.
the EPA could easily declare leaded fuel a danger to public health... That would start the clock ticking and all the carefully planned processes might go up in smoke.
Just how do you anticipate that starts the clock ticking? The EPA has been enjoined by no less than the Supreme Court to leave avgas regulation to the FAA, since the Bush administration didn't want to get involved in mediating between their two executive department agencies, so set up the courts as the bad guys.
