They've officially said:
CableCARD Features and Limitations (cox.com)
Due to the evolving use of the Internet to view and transmit video programming, Cox must make network upgrades to ensure its programming remains secure. It may be necessary to contact the equipment provider for CableCARD-ready devices to upgrade your device.
Note: PC-based CableCARD devices, such as HDHomeRun Prime from Silicon Dust, TV Wonder from ATI, or InfiniTV from Ceton, require Windows Media Center to record and may be required to view copy-protected channels.
I'm not currently sure if this is the end of life for all CableCards, but I'm unsure if they are going to reverse this change.