This has been driving me insane lately. I remember that Dan Carlin mentioned in his "Logical Insanity" series that some journalist or author wrote about how a World War was impossible in the weeks after Franz Ferdinand's assassination. He wrote something along the lines of "the world is too globalized for such a massive conflict to take place. Nobody is willing to throw away such an intricate and profitable system for one war."
Google has been no help and re-listening to the podcast yielded no results. Can anyone help?
The author you're thinking about is almost certainly Norman Angell and his book The Great Illusion. It was published several years before WWI, though (the original pamphlet that the book was based on came out in 1909).
Angell didn't say that war was impossible, just irrational and self-defeating. His thesis (there's a synopsis on page ix here) was the main justification for war at the time was a nation's need for outlets for its expanding population and industry, but modern economic arrangements rely on things like intricate credit arrangements that require respect for even enemy property. So (for instance) when Germany annexed Alsace in 1871, this didn't mean that Germans got a swath of new land to settle, it just meant that the German government had more land to administer.
You might be thinking about Jan Gotlib Bloch who wrote a series of books in the late 1890s analysing what would happen should the great european powers go to war with each other. The entire series was not translated into English, but a single volume summary was under the title "Is War Now Impossible?" However he did not actually argue that war was impossible. His, frighteningly accurate, analysis simply showed that it should be unthinkable as it would lead to the total collapse of at least one of the belligerents.