Around a decade seems like a realistic time frame to me. In my opinion, two big factors driving the collapse are climate change and the rise of BRICS.
US is seeing an increasing number of environmental disasters every year, and this puts pressure on the already ailing infrastructure. Changing climate is also causing droughts that will make large parts of the country unlivable leading to internal migrations of millions of people. The droughts are also causing harvest failures that will eventually result in food shortages. US farming practices also contribute to the problem because they cause soil erosion. I expect that these factors will significantly accelerate the internal conflict within US that's currently building.
Meanwhile, BRICS is creating an alternative economy that's outside western control and that necessarily means that the dollar based economy is now shrinking. Much of the wealth in US and other western countries comes from exploitation of the Global South, and when that stops there's going to be a huge economic disaster in the west.