Historically, the cable operators have been losing subs for more than a few years now while telco and satellite have been doing a better job of growing subscribers. Cable operators have been able to manage this loss because telephone and broadband subscription have been growing and the profit margins on these two businesses are higher than cable.
As to the causes, housing starts, unemployment, and costs of service are all to blame. As overall subscription has been rising, many argue that cord cutting is not a factor. But as more and more programming finds itself on the web, consumers may just start to move over to these OTT platforms. For now there is movement, but within the cable platform from operator to satellite to telco platform.