EW interviews the returning Harold Perrineau, aka Michael Dawson. Not a whole lot of interesting info as it relates to the show, but there is a little snippet on his comic-con comments on who's in the coffin... I won't quote that here, it could be a little spoilerish.
Did you know since you left that you would come back?
The idea was [Michael] was coming back, because he didn't die. [He and his son] jumped on a boat. So the question was always how and/or when he'd come back.
Link:
''Lost'': Harold Perrineau on coming back | Harold Perrineau | The Q&A | TV | Entertainment Weekly | 1