I'm pretty sure Ed Bernero is not a forgive-and-forget kind of guy, so I don't see Mandy ever coming back to CM even in a guest spot. Not to mention Thomas Gibson in particular seemed very hurt by Mandy. And the writers haven't really been kind to his memory (I think of Rossi in particular making derisive remarks about how Gideon left). I don't think he'd get a warm welcome from the cast/crew, even if there are fans who would want to see it. Plus, didn't he kill Three Rivers? I don't think that's on anymore. :P