According to this article, The Office finale will be an hour long.  But Steve Carell is unlikely to return as The World's Best Boss, Michael G. Scott.

""I’m hopeful, but I don’t think [Steve] will be back,” NBC Chairman Robert Greenblatt told reporters."

NBC Boss Robert Greenblatt went on to say:

"I think the decision is that he [doesn't want to compromise] his [original] exit.”

The airdate of the finale has yet to be officially announced, but the rumor is that it will air May 9th, 2013.

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