It would give the otherwise 'useless' commodities such as Water, Oxygen, stuff like that some actual trade value. Because no one ever trades those.
I think the reset value for the 'demand' would have to be very quick, or certain corporations will run out of goods to run to their bases. If 5000 water dropped the demand of a station by half for an entire day, for example, then that entire run would pretty much be screwed. And there's only so many commodites, and the ratio of traders:goods favours traders greatly...
Either it will have to take tens of thousands of goods to make a change to the demand, or the demand will have to return very quickly.
Also, what happens after a server restart? Does the dynamic economy pick up where it left off or does it reset to it's original value and the cycle starts again?
I'd predict if that happens, the made 'trader rush' will be worse than the 'code rush' after a server restart.
Also, if we can impliment negative effects against a base for lack of supplies (maybe goods/equipment cost more on the base, or something) then it will give 'cutting off the supply route' a real reason for factions like the Privateers.