IMO Marinelli is more important to retain than Kiffen.
I dunno. Kiffin's calling has been very good. It's one thing to have the philosophy down to a science it's another to apply it. There's also something to be said for feel of the game.
I almost get the feeling that Marinelli is comfortable with his DL responsibilities at this point in his career. He seems to love coaching that position and the players he coaches seem to love working underneath the guy. I can't imagine he's going to be looked at for HC jobs and outside of being a HC in Detroit for a couple years I don't think he's worked with anyone other than Kiffin and Lovie in the NFL.
I imagine it would be a tough decision for him but one that all three guys would understand if he was offered a DC job by Lovie. All three seem to be incredibly loyal and very close.
Pay won't be an issue because Jerry would pay as much as a DC job would. I guess it comes down to if he wants the added responsibility and commitment that comes with orchestrating the entire defense instead of a unit.