US economy has always fluctuated, it's part of capitolism. Our crests are always followed by troughs. Take for example the great depression, americas lowest economic point by general consensus. a decade later we are the strongest nation in the world and our economy booms. Before the great depression was the roaring 20's. When coolidge was president our economy was also doing well. The economic boom of the 50's and 60's was followed by the 70's, when we had products starting to be manufactured and imported from other countries.
If precedent holds true, I feel that we will reach an economic crest when the baby boomers begin to die of and we have a surplus from not spending as much on SS and medicare. I feel that then, depending on who's in charge and if they're fiscally responsible, We can put our debt in the billions if not millions. Paying off our debt can be done, it's just not gonna be easy. Major budget cuts and tax raises for I'd say 2 decades.
The problem with that is that no politician wants to raise taxes and cut benefits. It's bittersweet.