Rumor: Microsoft working on first party sequel for next Xbox console

EGM's Quartermann (or, as we at the Joystiq offices like to call him, ScoopMaster Q) reports that he recently caught wind of a heretofore unannounced Microsoft project -- a sequel to one of their first party titles, which is being developed for the next Xbox console. Apparently, the game was being developed for the Xbox 360, but for reasons unknown, the company recently decided to postpone the game, putting it instead on their next system.

While it's no surprise that there will be another Microsoft gaming console (Xbox 720? 361? Ybox?), nor is it particularly strange for a company to work on games for a system before its release (or announcement), it is peculiar that this news, if true, comes pretty soon in the Xbox 360's life. Considering that Microsoft has repeatedly said that the 360 will outlast the usual five year console cycle, why would they start working on games for a new system just a little over two years after the 360 came out? Consider one of our eyebrows officially raised in skepticism.