On basically all metrics the US is most prosperous country on earth. Our middle class turned into upper class. It's a pretty bad argument when the poorest part of the country are richer than basically anywhere else in the world. The only argument I could entertain on this line of thought is that the US has reached it's peak (today) and may decline. That atleast has merit because there's a good argument the AI bubble popping could lead to a chain reaction causing long term decline. But saying the US has currently declined is crazy when seeing the previous 2 years. Maybe the argument is that the craziness the US has been doing is "burning" its potential for short term gaibs for long term damage. Totally possible but there really isn't an argument to be had that the US is currently some weak or lost cause as of now.
EU is struggling for a lot of reasons the US was supporting the bad design. I do believe it's a kind of learned helplessness though and youre right. If EU stopped social spending reduced regulations rebuilt their military they could actually make a come back in like 15yrs. Sounds like a long time but that actually is really good and their recent discussions on actually rebuilding their militaries is a glimmer of hope. But the greatness of europe like it was in the past? As of now a totally lost cause and that's cultural. Until the current generation dies and people who want to see europe be a real power again come up there's no way. France would be my bet on this front.
An actual failure of a super power is britain. That's what it looks like when a super power has "lost" the only question to ask is wether US is currently in it's 1700 British empire mode or 1940 one.
Everyone has said how the us is failing for literally my entire life now. They intensified in 2016 with oramge man's first term and continued to now. But again, in realistic terms the US is not less than it was a decade ago and in obvious terms it's in a better position today since the 80s.
The most obvious example is energy. Middle east and venuzuela were basically light advesaries. Saudi was leaning towards china. Now? US essentially controls the majority of oil in the entire world. Nobody else can put a fleet of ships on the output of ME like that. Sure Iran can commit terrorism on civilians but nobody can drop an army anywhere in the world like the US. Our arab allies have heavily realigned to the US. Our oil is the highest output ever. Venuzuela is ours so in 15yrs so is the next middle east of oil output.
So again. World energy dominance for the next 50yrs minimum. We have the largest datacenter capacity by a stupidly large margin. Possibly in 20yrs a complete monopoly on industrial space flight. Those 3 things together to me are a near garauntee dominance. Even one of those things could be enough to stay a super power but all of them? All at once? That's a wild combo. No other country even has one of those (i suppose ME countries with oil is the only one).
We'll see how Iran turns out though. That would be the chink in the output above. State sponsored civilian terrorism is a hard thing to stop but they have succeeded in aligning every arab ally against them pretty good.