"Collapse" means suddenly crumble, cease to exist.
Well, it means the former not the latter. A collapsed building is still a building.
Can you really imagine the ecological / economical limits described here to eliminate every sort of organized production on Earth?
It doesn't have to eliminate every bit of production. We had a pretty substantial mess just from a recent real estate crisis.
And if you look at the historical examples given in the story, they didn't actually collapse suddenly. The scenario given is that things got progressively worse with the people in charge not doing enough or often making things worse.
For example, the Roman empire was in deep trouble in the third century. One of its effects was to severely damage various bits of infrastructure both physical and legal. For example, the trade network that the Romans had set up never became as safe as it had been. Also, the mess had created considerable inflation and the previously mentioned shift to concentration of wealth to large land owners.
They also overlook the adaptability of demand when the supply shortens, and the number of disruptive technologies appearing every day, rendering moot any such "if the trend continues" analysis.
The problem here is that the markets and other infrastructure which enables transactions between demand and supply is what can fail.
For example, I've heard it predicted that once Obamacare gets fully implemented it'll stop future drug development over our lifetimes. I guess the idea is that somehow all drug development throughout the world only happens in the US due to companies or something. Obviously, the prediction is a bit overwrought, but that sort of thing is what leads to long term disruptions between supply and demand.