I put the collapse of Britain's empire at around 75 years, which is faster than the Ottomans or Spanish empires, but still nothing compared to the Soviets, which to reiterate, was an historical anomaly.
As for the US, for all the current turmoil, the dollar is still supreme in global economics, its soft power is still immense, despite the immigration chaos its still the primary destination for immigrants, and it would take decades for countries to push out our military bases because doing so would often mean building up their own military infrastructure.
Trump's unconstitutionality is a threat, and that the US has a series of bubbles built on shaky economics is not controversial. But I don't see how that could possibly result in a Soviet style singular day of collapse. At least internally, there isn't a cultural and linguistic separation between states the way there was with Russian imposition on their Soviet satellite countries.
And of course, there's the previously mentioned shock therapy, something that wouldn't have the same level of violent effect because the US is already a market economy. And there's nobody powerful enough to impose something like that on us regardless. Unlike the Soviets, if the US goes down, much of the world goes down with us, so there's strong incentives for an off-ramp, not a destabilization.
I agree there are major structural issues, and the US democratic system is being stress tested daily, but its all symptoms of decline, not imminent collapse.