Given John's penchant for cyclical models of history, you shouldn't be surprised to hear that if Germany had won World War I, not much would have changed. We like to think of battles and wars as momentous things, and sometimes they are, but the outcome of the twentieth century was overdetermined, at least according to Spengler and Toynbee.
By way of proof, consider this: Spengler started writing the Decline of the West in 1911, and finished it in 1914. Weimar culture, famed for its decadence and defeatism, started before the war too. Its analogues started in England, France, and the United States about the same time.
Here is John's boldest claim:
I would go so far as to say this: something very like the Nazi Party would still have come to power in Germany, even if that country had won the First World War. I realize that this assertion runs counter to the historiography of most of this century, but the conclusion is inescapable. Politics is a part of culture, and the Nazis represented a kind of politics which was integral with Weimar culture. Salvador Dali once said, perhaps ironically, that he approved of the Nazi Party because they represented the surrealists come to power. The connection is deep, as with the Nazi affinity for the modernist post-rationalism of the philosopher Heidigger, and also superficial, in the styles the party promoted. The Nuremberg Rallies, for instance, were masterpieces of Art Deco stagecraft, particularly Albert Speer's "cathedral of ice" effect, created with the use of searchlights. As a young hopeful in Vienna, Hitler once passed up the chance to work as a theatrical set designer because he was too shy to go to the interview. But whether he knew it or not, that is what he became. People with no fascist inclinations at all love to watch film footage produced by the Nazis, for the simple reason that it is very good cinema: it comes from the same artistic culture which gave us METROPOLIS and THE BLUE ANGEL. The Weimar Republic and the Third Reich formed a historical unit, one whose advent was not dependent on the accident of who won the First World War.
Leni Riefenstahl deserves mention here too. A Triumph of the Will was a masterpiece of a movie, and continues to be influential today, although no one would be so foolish as to admit it influenced them. The Nazis were stylish and popular, a reflection of the spirit of the times.
John gets even more contrary towards the end. He suggests that despite the colossal waste and horror of the Great War, the way it turned out may have been better than some of the likely alternatives. This is worth considering.
In a way, this is a more interesting hypothesis than the more commonly asked question about what the world would be like if the Germans had won World War II. Several historians have noted that both world wars should really be considered a single conflict with a long armistice in the middle. If this viewpoint is valid, then the official outcome of the first phase of this conflict may have been important for reasons other than those usually cited.
As a preliminary matter, we should note that the actual outcome of the First World War was a near thing, a far nearer thing than was the outcome of World War II after 1941. While it is true that the United States entered the war on the allied side in 1917, thus providing vast new potential sources of men and material, it is also true that Germany had knocked Russia out of the war at about the same time. This gave the Germans access to the resources of Eastern Europe and freed their troops for deployment to the West. The German Spring Offensive of 1918 actually succeeded in rupturing the Allied line at a point where the Allies had no significant reserves. (At about this time, British Prime Minister Lloyd George was heard to remark, "We are going to lose this war." He began to create a record which would shift the blame to others.) The British Summer Offensive of the same year similarly breached the German lines, but did a much better job of exploiting the breakthrough than the Germans had done a few months earlier. General Ludendorff panicked and demanded that the government seek an armistice. The German army did succeed in containing the Allied breakthrough, but meanwhile the German diplomats had opened tentative armistice discussions with the United States. Given U.S. President Wilson's penchant for diplomacy by press-release, the discussions could not be broken off even though the German military situation was no longer critical. While the Germans were not militarily defeated, or even economically desperate, the government and general public saw no prospect of winning. Presented with the possibility of negotiating a settlement, their willingness to continue the conflict simply dissolved.