being specific about manufacturing’s decline in the US
While it’s true that there are still millions of factory workers in the US, there has been a dramatic decline in manufacturing jobs as a percentage of the total workforce. And not only have the large majority of these jobs been shipped to sweatshops overseas, but as you pointed out, those manufacturing jobs that remain in the US today aren’t the same as 30 years ago: the pay is lower, the hours are longer, the benefits have been cut, and the unions have been busted.
… but I don’t know that I’d call this a collapse either. They have actually increased the scale of manufacturing, and have simply relocated it to other parts of the world with cheaper or free labor. The capitalists are now making more money and consuming more resources than they ever have before. So while one can say that U.S. manufacturing has declined/collapsed, I don’t think it’s true at this point that capitalist manufacturing has declined/collapsed (although it inevitably will in the near future as a result of depleted resources and popular resistance).