A website called Develop seems to have important information about the launch of Microsoft's next console. Their sources indicate, "from chip manufactures to middleware firms," the next Xbox will be revealed at E3 2013 and have an intended release date for the same year (even though it's likely to slip into 2014).
There has been no official word from Microsoft on the matter. It's tough to believe rumors like this when the past couple years have been flooded with stories about the next Xbox. Earlier this year, a snitch from EA claimed they already had the dev kits for the new console. Other developers also had leaks that game development was already starting on the new console as well. Although, most of these rumors claim the unveiling will be sooner at E3 2012. Reports of job listings about the development of the next Xbox have also surfaced.
There's obviously no way to tell if the developer's leaks are correct until next year, or if Develop's information is accurate until the year after. Keep in mind, half the rumors about the next Xbox have already been debunked. I remember a story a few years ago claiming Elder Scrolls 5 was going to be an MMO for the next Xbox. Patience young Jedi, and our console will reveal itself.