I think one can easily make parallels between the collapse of the USSR and the way the USA seems to be going, and more broadly other nations, contemporary and historical. The main issue is a lack of belief in the national vision, or simply a lack of fear of the regime.
This can be down to various things; falling living standards are a major influence, most notable example being the great depression; which led to the communists and fascists in Germany replacing liberals and conservatives as the political mainstream and the Weimar Republic no longer being believed in. Or a harder to pin down malaise. The Soviet Union gradually became more and more corrupt and cynical. Even if the Soviets didn't know about the outside world, they knew the system was becoming rotten as their mission objective became less and less likely (world socialist revolution), and even more so if they knew of the outside world's progress and their own stagnation. Why would you bother if you knew your efforts were really for nothing? It's the same mentality, sadly, which afflicts those stuck in poverty. Why save any money if you can never afford a mortgage? Which then makes things worse.
The USA is suffering from something weirder, since anti-government sentiment runs very strongly in many places which actually benefit a great deal from public services so endemic they have become invisible, and yet though living standards in the USA have stagnated for most people it's nowhere near the poverty and starvation in the Weimar Republic. People believe government can't do anything, and so government begins to believe it can't, or perversely, to actually make sure it can't.
But disillusionment won't on its own be an issue if the state is vicious enough to make everyone terrified of not doing their best. The Soviets didn't fight tooth and nail in Stalingrad because they loved their nation, but because they knew if they retreated they'd be shot. The Nazis also fought with vicious bitterness because they thought themselves in a war of annihilation; if it's victory or death you don't much care for risking death to achieve victory.
So we can compare the USSR to North Korea, and ask; why is North Korea still around and the USSR long gone? One idea is that North Korea never underwent deStalinisation, and the USSR did. Stalin did well, not because he was very clever, but because he was a tyrant who tolerated absolutely no dissent. The second world war could have been won in half the time and with half the Russian losses if he hadn't have gutted the army and nation of its best men and women prior to being invaded. If the USSR didn't have the disproportionate natural resources, space, and manpower, compared to Germany, it would absolutely have lost the war. After Stalin the USSR became less and less authoritarian and more and more corrupt, to the point where the leader of the nation proposed reforms which were put down with tanks years prior (Gorbachev described the difference between his Glasnost reforms, and the reforms proposed by Czechoslovakia which were put down with Warsaw Pact tanks, as "19 years"). And when those reforms were enacted it all fell apart. The point is: North Korea plods along, and things fall apart and break not because of corruption (arguable I know given the Kim dynasty), but because they've simply run out of materials. They will try their best to impress the dear leader... but if they physically can't do it, they will die trying and still fail.
Another reason for disillusionment can be the very lack of the nationalism itself required to keep a nation together, or indeed another unifying factor like state religion or monarchy. Historically most peoples in any kingdom didn't regard themselves as being from the same tribe as the King; but they didn't need to if they believed in/were shit scared of their leader. In many contemporary less developed nations the people generally don't identify with or believe in the nation. They have tribal or religious loyalties which divide them from one another, and in this case they would rather enrich their group at the expense of a state. National unity is a very important thing, and yet barely spoken of these days. We don't just see this in places like Africa, but also in how the Middle East has been disintegrating lately. There simply isn't a belief in national institutions, and they perhaps can't even do their job.
Regarding the requested answer: I would caution that a major power doesn't necessarily have to be doing things "right" to achieve its power. That could be part of why it collapses: its success was a fluke and that was unsustainable. But an unsolvable problem would be that the nation can't meet its objectives, or indeed has lost its confidence to the point of national suicide.
It could also be said that when a group lacks a threat, it becomes corrupt because it doesn't need to do well to exist. Look at South African Apartheid. The regime was wicked, but for white Boers they held together as a community and did the best they could, because they knew that if white rule ended they could all be killed in a black communist revolution (ironically backed by the same forces I describe as having lost their own enthusiasm for world revolution). I doubt it's coincidence that it has been suspected but never proved that Apartheid South Africa and Israel conducted a nuclear test in the pacific together... but since the fall of Apartheid, South Africa's corruption has become so bad that its spy agencies were embroiled in a corruption scandal a few years ago for selling state secrets to everyone.
The USSR is a good example to speak of with regards to their inability to complete their mission objectives. Soon after the second world war ended it became obvious that they couldn't conquer western Europe. Soviet military officers regarded the end of war as their zenith, and since then they had declined in every measurable way compared to their NATO rivals. By the 1960s Soviet officers worried they couldn't beat the West German Bundeswehr in a fight, nevermind all of NATO. And as the Vietnam War began America's fear of "domino theory" turned out to be short sighted. By then the Soviets and Chinese, who had prior been a united front willing to cooperate to bring about a communist revolution worldwide, fell out. And with that split neither could achieve its end game. They could only consolidate to Stalin's "socialism in one country", or the bloodthirsty cultural revolution in China designed to purge the collective mind of all alternatives.
In summary: lack of national unity (due to multiple ethic groups, religious groups, and ideological groups), impossible national objectives (or failing national institutions), lack of existential threat (internal or external), lack of authoritarianism, economic decline or stagnation. Put them all together and your situation will definitely be unsolvable!
P.S. Sorry for it being long and rambling, the question draws on many historical contexts.