It's fun to think about this stuff, but like the YouTube comments discuss, this is not going to be a practical solution. The cost:benefit ratio just isn't there.

My personal opinion is that continued electrification of existing transport modalities is probably going to be the defining feature of future transportation developments for the next century. The biggest issue is battery energy density, but I'd be shocked if things like solid state batteries didn't start coming online within the next decade or two. There's just so much investment going on here right now.

So obviously things like electric cars and buses on existing roadways is going to continue growing. Full self driving will eventually occur. Convoys of high speed electric vehicles traveling down highways will basically do everything that high speed rail is supposed to do, but without the need to build high speed rail. Like by the time a transcontinental high speed rail system would be built (50 years?) It would be obsolete.

That's not even taking into account how the enormous investment and innovation fueled by the electric car/truck/bus industry is also going to enable electric airplanes. Being able to fly a couple dozen people to local air strips a couple hundred miles apart will be a true transportation revolution. You'll be able to connect up all these regional locations without any significant infrastructure and at aircraft speeds and for relatively low cost.

High speed rail is amazing for high density locations like Europe, Japan and China. But for the USA it's a much tougher sell. And with upcoming developments in electric vehicles it's likely to be obsolete by the time you finish building it. It's sort of like trying to convince a big African country with poor telecom infrastructure to build out a national network of expensive high speed fiber optic cables instead of going for something like wireless cell towers or just switching to satellite constellations like Starlink in another decade.