Instead of halting releases of virus signature updates when they retire support for Windows XP in April, the company announced that they'll continue updating XP versions of their Microsoft Security Essentials, offered free for consumers, as well as their corporate offerings, System Center Endpoint Protection, Forefront Client Security, Forefront Endpoint Protection and Windows Intune, through July 14, 2015.
In a posting to their Malware Protection Center Web site, the company reiterates their encouragement that users update to a more modern Windows operating system. Up-to-date antivirus definitions, they say, are only part of what makes a secure system. They don't replace running a modern operating system with regular security updates.
The company also clarifies what it means that Windows XP will become a non-supported operating system after April 8, 2014 by saying, "Windows XP users will no longer receive new security updates, non-security hotfixes, free or paid assisted support options or online technical content updates from Microsoft."