A few comments:
Dirigibles have been around for a long time and are extremely safe and efficient. This is not "science fiction becoming science fact," it is merely a very positive evolution of an existing technology.
I do not believe the claim of 100 mph. Airships have very large surface area, therefore massive drag. To propel one of these at 100 mph would require so much energy it would be impractical.
The fire that destroyed the Hindenburg was not the hydrogen burning. It was the skin of the airship burning. The skin was a lightweight fabric made airtight by a doping compound which was highly flammable, and was ignited by the spark. The people who died in the tragedy were those who panicked and jumped to their deaths. Those who remained on board were mostly unharmed as the gondola settled slowly to the ground as the hydrogen escaped.
Mixing nitrogen (or any other gas other than helium) with the hydrogen will do no good. It will just make the gas heavier and therefore less buoyant. Helium and hydrogen are the only gasses that will work. Hydrogen is not free or 'easy" to produce. It requires energy to drive electrolysis (the separation of hydrogen from oxygen of the water molecule). But it's still much cheaper and more easily available than helium, which it would be good to conserve for applications where there is no other substitute, such as welding aluminum or deep-sea diving.
An airship held aloft by a vacuum is pure fantasy. It's not science and not even science fiction. There is no material known or reasonable to expect that is at once strong enough to resist the atmospheric pressure of 32 pounds per square inch and light enough for an airship which must, in the end, be lighter overall than the amount of air it displaces. A vacuum bottle will keep your coffee warm, but it will never be lighter than air.
Dirigibles are great for lifting and moving very large, heavy loads, and for carrying them over land or water. Equipped with luxury accommodations they are great for moving people who are not in a hurry. (Sort of like cruise ships.) They are susceptible to bad weather, but with present-day weather satellites, that can be worked around. They are very efficient. The flammability of hydrogen is not a problem except for the public perception. The hysterical radio announcer who famously reported on the crash of the Hindenburg did the world a great disservice, and subsequent reporting which emphasized the hydrogen rather than the real culprit: the flammable fabric doping, sealed the demise of the dirigible. Nowadays there are bound to be non-flammable materials. Dirigibles won't replace airplanes, because airplanes are much faster, and people are so often in a hurry. But there are many applications where they are ideal. Maybe the aircraft reported on in the article will re-introduce this promising old technology to a world badly in need of more efficient transportation.
Dale is actually very forward-thinking in using dirigibles in his books. They are not science fiction and they are not fantasy, though Dale does use fantasy for their propulsion. There is no technological reason not to build lots of them right now (with, of course, conventional motors).
