Remember reading an interview not long ago where Michaels said he's been trying to retire for the past three years, but Vince has always needed him. Giving that he's a pastor or something back in Texas, I can see Michaels retiring this year (if not, definitely next) and then saying good-bye to wrestling for ever.
I'm thinking he gets so desperate that he puts his career on the line to get the Deadman - and despite an incredible effort and a five-star match, he just loses, at which point he leaves with much fanfare etc. We'd have a WrestleMania where both Hart and Michaels get their moment in the sun, and maybe Cena/Batista too, which is probably the big match of the current era.