Capitalism is not the problem so much as policies that promote trade imbalances and outsourcing of jobs. If there are people somewhere willing to work for much less than you are, there are far fewer opportunities to do anything. It is not normal to get a ton of cheap imports forever, and a reversion to the mean is not a sign that capitalism is failing.
Unless the whole world was to demand the same standard of living (which is impossible), or global trade is limited, there will be nations where the wealth of the average person is on the decline.
What we are seeing is a great levelling out of living standards across the world. Poor countries are unquestionably getting richer, while rich countries are stagnating and decaying. It's a period of readjustment, but self-limiting.
There's no need for the West to stagnate like this. We could let the rest of the world develop itself while we continue to be self-sufficient. That requires tough decisions like choosing to limit imports of foreign goods and labor. But that is unfortunately not how it's going. Some people have been selling out their own countries for decades to make a quick buck, or perhaps to defend some economic theory that the plan with the highest cost efficiency is always the best.