Pondering the "American Century"

Two excerpts from an essay in Harper's Magazine.
First, the intro -
In February 1941, as Adolf Hitler’s armies prepared to invade the Soviet Union, the wingnut oligarch and publisher Henry Luce laid out a vision for global domination in an article titled The American Century. World War II, he argued, was the result of the United States’ immature refusal to accept the mantle of world leadership after the British Empire had begun to deteriorate in the wake of World War I. American foolishness, the millionaire claimed, had provided space for Nazi Germany’s rise. The only way to rectify this mistake and prevent future conflict was for the United States to join the Allied effort and "accept wholeheartedly our duty and our opportunity as the most powerful and vital nation in the world and... exert upon the world the full impact of our influence, for such purposes as we see fit and by such means as we see fit."
Just as the United States had conquered the American West, the nation would subdue, civilize, and remake international relations.
Ten months after Luce published his essay, the Japanese attacked Pearl Harbor, and the United States, which had already been aiding the Allies, officially entered the war. Over the next four years, a broad swath of the foreign policy elite arrived at Luce’s conclusion: the only way to guarantee the world’s safety was for the United States to dominate it. By war’s end, Americans had accepted this righteous duty, of becoming, in Luce’s words, “the powerhouse.... lifting the life of mankind from the level of the beasts to what the Psalmist called a little lower than the angels.” The American Century had arrived....
Then at the midpoint of the article -
The more one considers the American Century, in fact, the more our tenure as global hegemon resembles a historical aberration. Geopolitical circumstances are unlikely to allow another country to become as powerful as the United States has been for much of the past seven decades. In 1945, when the nation first emerged triumphant on the world stage, its might was staggering. The United States produced half the world’s manufactured goods, was the source of one third of the world’s exports, served as the global creditor, enjoyed a nuclear monopoly, and controlled an unprecedented military colossus. Its closest competitor was a crippled Soviet Union struggling to recover from the loss of more than twenty million citizens and the devastation of significant amounts of its territory.
The United States’ power was similarly astounding after the Soviet Union’s collapse in the early Nineties, especially when one aggregates its strength with that of its Western allies. In 1992, the G7 countries—Canada, France, Germany, Italy, Japan, the United Kingdom, and the United States—controlled 68 percent of global GDP, and maintained sophisticated militaries, which, the Gulf War seemed to demonstrate, could achieve their objectives quickly, cheaply, and with minimal loss of Western life.
But this is no longer the case. By 2020, the G7’s GDP had dwindled to 31 percent of the global total and is expected to fall to 29 percent by 2024. This trend will likely continue. And if the past thirty years of American war have demonstrated anything, it’s that sophisticated militaries do not always achieve their intended political objectives. The United States and its allies aren’t what they once were. Hegemony was an anomaly, an accident of history unlikely to be repeated, at least in the foreseeable future.
Conclusion and more at Harper's.