The collapse of the Soviet Union was ahistorical in many ways. It's rare that collapse of an empire can be pinpointed to a single day. And what you saw was a result of shock therapy imposed from the outside. I doubt that would happen to the US.
It's unlikely collapse will be felt as a singular, apocalyptic event. More like a slow, steady loss of influence and excess wealth. Countries on the periphery stop considering the empire's perspectives before making their own decisions. Other trading partners emerge. Bridges stop getting maintained until they're no longer usable.
And soft power declines. Imagine a day when the biggest pop star in the US, someone on the scale of Michael Jackson or Madonna nationally, is virtually unknown outside of its borders.
There are reasons to believe the American empire is in decline, but I maintain this will look more like Britain. It could take 50 years before American fully realize it.
Thankfully, that means there's plenty of time to reverse or mitigate the trends, or to make a decision to strengthen the Republic over the Empire.
Britain's demise was relatively swift, and took place over the course of the two world wars. It fell almost immediately into vassalage, under the US. Not quite a bang, but not as drawn out as you suggest.
Its former colonies experienced all I described above and more. In this case, the colonies are most of the world: where are the bases? Everywhere.
With the States, here's the scenario, not too far fetched. We will see 1) constitutional breakdown, as Trump (or his crew) digs in, and 2) economic breakdown, 2008 but exponentially worse.
This would constitute a Soviet scale collapse, to my mind.
I beg to differ. The collapse of USSR was 100% caused by internal causes.
First was the abominable low productivity in oil/gas and agricultural sectors from 1950s through 1980s.
Then came the corruption of Brezhnev era. Andropov tried to get some reforms going: first against corruption and then some Chinese-style economic changes. But Andropov died very quickly.
Eventually came Gorbachev- who had good intentions. Unfortunately he prioritized political reforms over economic. He wanted economic reforms with no pain, something to show his people some progress. Unfortunately that was impossible so he ended up with some half baked ideas (like limit alcohol sales. Or letting factory managers keep their profits expecting the managers to invest profits in new technology- managers used the profits to pay themselves. Or introduce free markets pricing between factories-when managers complained they had to pay market prices on inputs and nobody were buying their outputs the result was to subsidize factories for both inputs and outputs)
The result of these Econ reforms was that the Soviet state was running out of money. (A humanitarian policy was that for the first time in Russia’s history bad agricultural results did not result in famine-for the first time the govt bought food on the international market paying in Western currencies)
Add a few ambitious politicians who did not want to take orders from the center (Yeltsin being the principal example, but also Kravchuk) and the process of dissolution already started by the Baltic independence could only end with total collapse.
The shock therapy you mention was designed, advocated, and ultimately implemented by Gaidar - a Soviet economist fully trained by the Soviet state.
Sorry for the long reply. If you are interested in this topic I recommend reading two books, both called “Collapse” one written by Gaidar, the other one written by Zubok.