I agree that we are not currently flying MD-11, but that's just because of the November tragedy. I don't think they are going to retire it if not because of it. That is, they retire it out of scare of more tragedy, not because of older age.
MD-11s aren't in commercial passenger service, so it's unlikely they retire it due to a poor reputation.
The huge question is what changes the FAA requires to unground it; if they decide design changes are needed to reduce the risk that an uncontained failure of engine 1 or 3 directly takes out engine 2, that could likely be economically infeasible.
