The Future from 1966
Popular Science describes plans for a 4,000 mph underwater train under the Atlantic that will make it possible to simply zip across the ocean -- "allow you to have lunch in Manhattan and still get to London in time for the theater, despite the 5-hour time difference". Concept is simple. Just construct a 3,500 mile long neutrally buoyant (floating) tunnel at a safe depth under the ocean, pump all the air out of it to remove air resistance and put maglev rails on it.
A number of practical objections suggest themselves. One is how you construct a 3,500 mile long pressure hull and ensure watertight integrity; the other is how easy it is to make a 3,500 mile long vacuum chamber. But that's not the point. It's a wow idea, like flying cars, jetpacks, domed cities and ... that makes one wonder whether it won't wind up like the other cool stuff that once seemed just around the corner and never materialized.
One problem with visions of the future, according to some, is that they are usually extensions of our present day ideas. They are what we imagine the future to be like in terms of what we know today. It is not the future that actually eventuates.
Typically, complex problems of the day are solved with new wonderful emerging technologies. But in reality the technology is grounded in that of the day, mere off-shoots of what was considered leading edge. In hindsight, it is unlikely that the technology could have achieved a fraction of what was imagined.
The imagined future either never comes as imagined (being infeasible as extension of the past technology) or it is altogether more wonderful, based on methods unforeseen. Consider this home office of the future, circa 1966. We can do almost everything predicted in that long ago year, but very little of it in the way envisioned.