There has never been a country as cultural influential as the United States. The US is the only country with a military presence the spans the globe. In tech, you could combine the rest of the world and the US would still be ahead. Europe had to create a union to create a market big enough to compete with the US.

I don't think you understand the scale at which the US has to absolutely continuously fail over the next century to lose its lead.

I don't deny that US is still by the far the greatest country on earth currently. In fact I said that myself.

But there is no such thing called as a permanent super power, nor there ever will be.

Everything that you wrote about US, could have been written about any super power in History. The Romans, The Mongols, The Greeks they all were super powers with similar traits. And yet none of them are a super power today.

You underestimate how decadence works. There are a lot of Chinese and Indians who no longer want to come to US. And it takes a very few companies to change the economic momentum of the world. If past is any indication, you could even alter the very direction of the human race with a few inventions/enterprises, and you can do it quickly.

The most far fetched part isn't that the US might fail, it's that Canada would take its place out of all the other nations. The growth figures make this idea nonsensical, unless Canada somehow invents a strong A.I. or some equally implausible scenario.