Based on this data one can expect the USA which started being a "hegemon" under my methodology in 1900 to drop out of the top 2 in the world by around 2100 or 2120 at the latest.
Calling the USA a "hegemon" anytime prior to 1918 is really suspect, and frankly, I'd say it's unwarranted until 1945. You could make a case for the USA as the single most powerful nation in the world in the interwar period but it'd be a hotly contested case and it certainly wasn't obvious.
The USA does take the position as the world's highest GDP country in the 1880s and has held it continuously since (PR China will likely take the title in the early 2030s, but a 150 year run is incredible), and the USA was undoubtedly the hegemon of the Western Hemisphere during the late 19th century to present (in really negative ways, especially, in the early 20th century), but the idea that the USA had greater international influence than the UK or more formidable military prowess than Germany in 1900 is pretty laughable.
Sure. This is a word definition calibration issue. I merely defined "hegemon" as being in the top 2 powers in the world. I am happy to use a different word as I agree top 2 is a bit of a stretch for that word. My point is that from an amateurish and subjective statistical analysis one can say that the USA will fall out of the top 2 powers in the world by 2100 or 2120.