This actually sounds pretty interesting... I wonder what it'll be like. I'm glad RE6 is getting story content.
The article simply states that it is a DLC that will be released in 2013 and star Leon as the protagonist. It also states that RE6 producer Hiroyuki Kobayashi believes he's found the reason why RE6 was poorly received, and that RE4 fans will likely enjoy this DLC
EDIT: One odd thing towards the bottom translates to "we are reducing the polygon count for this DLC". Might be my bad interpretation of that word, since I don't often speak Spanish.
Basically even if it's real, that sounds more like a re-re-re-release of RE4.