ArcGIS Online will be retiring it's existing cached demographic layers and moving to a new service, http://demographics1.arcgis.com/arcgis/rest/services/USA_Demographics_and_Boundaries/MapServer, which requires an AGOL subscription. The new service will consume credits.
If you are swapping out the old cached service for this new one there are a couple of additional steps to consume the service. This repository holds a sample application that demonstrates one way to consume the new service.