NamcoBandai Games has trademarked Soulcalibur: Lost Swords via the United States Patent and Trademark Office. As discovered by Videogamer, the trademark was registered last week. Perhaps we'll learn more at this week's San Diego Comic-Con.
The title could refer to the Soul Calibur and Soul Edge, the series' iconic blades which play important roles in the fiction. The Soul Edge ranked #60 on IGN's top 100 weapons list. It's worth noting that Lost Swords doesn't appear to be a proper, mainline sequel -- perhaps, instead of Soulcalibur VI, this is a pseudo-spinoff similar to 2007's Soulcalibur Legends.
Is a new Soulcalibur sequel in the works, and if so, is it coming to next-gen consoles? IGN has asked Namco for clarification, and will update this story with any response.
http://www.ign.com/articles/2013/07/18/soulcalibur-lost-swords-trademarked-by-namcobandai