If a city fails to meet its threshold, what does this mean?

Responses

It is not economically feasible for its market area to purchase goods and services from it.
The population grew to such a number that it needed to be considered a global city.
The population levels of the area have exceeded its food production for it to be viable.
The population it provides for lives too far away for it to remain relevant in the area.

If a city fails to meet its threshold, it means that it is not economically feasible for its market area to purchase goods and services from it. In other words, the city is not able to generate sufficient demand or support from its surrounding population to sustain its economic activities.