Let me rub your stomach and pat your head while your eyeballs project light that forms into a hologram telling me the future. Only then, can I entertain and answer your thoughtful question.
Was there a rumor going like if the MRI result shows no sign of problems in his knee,he would choose the day before his wife's b'day for his return?
He will come back to Houston on December 2012. He will mark the beginning of the rapture/apocalypse/7th season of Barney!