The current level of production can be sustained, but for ongoing growth in production what is needed is expansion in demand and prospects for demand are regarded as, to use the current language of choice, “uncertain”. It is not that demand is falling - it is growing. The issue is to what extent, and how soon, it might accelerate.
In this context, the behaviour of business investment has been nominated (by the Federal Reserve, for example) as crucial. After such a prolonged period of massive capital investment, there was a very sharp fall-off in capital spending by US businesses during 2001. It was this component of demand which was responsible for pushing the US into recession.