Board Thread:WARNING ALL USERS False Info\Spoilers/@comment-5.43.78.215-20130829112327/@comment-209.30.133.210-20130908024921

He could easily come back as a ghost, or a poltergheist or something, a one shot or two shot villain, someone who died a tragic death, and thus, is out for a little revenge (or a little More revenge).

They haven't laid down any means of barring the possiblity, so yeah, it's possible.