Presumably the rumored Comet game about reusing as many AC3 and AC4 assets as possible.
Source: http://www.ign.com/articles/2014/07/10/last-gen-assassins-creed-to-be-revealed-soonIGN said:During an investor call today, Ubisoft CEO Yves Guillemot said more information regarding a last-gen Assassin's Creed title could be on its way.
"More info on that soon," he said. "It will come soon."
This Assassin's Creed title may be Assassin's Creed Comet, which will allegedly star a Templar in North America. The title was originally leaked alongside the announcement of Assassin's Creed Unity, the next-gen title releasing this fall, but no new information has been revealed about the game for Xbox 360 and PS3.