In the short term, the manufacturer will either pocket the difference and spend it on a new Lexus or diamond necklace for his wife (employing more people); or he'll lower his price to undercut his competitors, increase his market share and make more profits anyway. In the end, the money doesn't disappear into a bourgeoise black hole. The manufacturer is human, therefore his wants are unlimited, therefore he will employ people in the process of meeting his wants.
By the way, if he doesn't drop the price of his couches, he's not very competitive; one of his competitors will wise up, make his own business more efficient in some way, and undercut his prices to increase his own market share and profits. If no one does this, or if they collude between themselves to keep prices higher than what they might be, than I, or someone just like me, will enter the market and take their market share by virtue of a better and more efficient business. That's what keeps the free market honest and efficient. In fact, the only thing that makes the system break down is when the interested parties collude with the government to protect them via things like tariffs on their products or new regulations to keep newcomers away (see the steel industry and the oil refineries).
He didn't move to Mexico to be nice to Americans...
No, but it's funny how the system works to make it seem like everybody loves us, isn't it?
Very good, so in you OWN "optimistic" scenario the prodcution will shift from providing the working people with American life standard to making diamond necklaces for the rich women. This is the pattern of Latin America and most of the Third World.