Since magic is declining and technology is rising steadily in arcanum, this could possibly mean that will completely dissappear if technology continues to rise at this pace. But that is not the only effects of the "Age of Technology" When humans start to dominate the world with their tech, the other races such as dwarves and elves can hardly defend themselves, since they áre no longer a superpower. Add the apparent racism that exist in arcanum and you can bet, that given the sufficent power the human race will start a mass genocide. Races such as elves or dwarves are not numerous or powerful enough to defend themselves from the highly advanced humans. The other races or monsters are also going to become extinct in few decades in a century or two. It's not the fall of magic that is being presented in arcanum it's also the fall of fantasy. A world where technology reigns as humans dominate the world, magick and fantastic races are simply tales of old. Of course all of this is just an speculation, but it still fun to think what will happen in the near or in the future of the world of Arcanum.
The fate of Arcanum is heavily depending on how you'll play the game and which ending you'll get. So it's not a fatality for magic to disappear.
According to a historian at the... Roseborough Inn, I think, magick and technology have always waxed and waned in Arcanum. So, whilst technology may be on the rise in 1885, it's hardly improbable that a new age of magick would dawn in 2200, say.
The dwarves are, I might add, much more technologically advanced than the humans in Arcanum. During the clan wars started by Lorek, they had machines which could possibly level mountains. Arcanum humans are not on par with that, they're not even on par with the tech of Vendigroth which existed 2000 years ago.