Another option could be a transition into a less-visible role prior to his expected departure date of sometime in 2014....
Was this expected? I figured after he returned he'd be sticking around for a bit.
I believe he was committed to staying "at least" through 2014. I'm not sure of the details of it all, of course. I just thought it could be a possibility--it would be odd for him to leave less than a year after being convinced to stick around for a bit (in my opinion; I don't know the guy.)
That's an excellent question, and one that this submission is definitely not going to answer.