First off, I don't want to even see Cox in the game. But, that's just me. I'm tired of his weenie arm, horrible decisions and cement-footed "scrambling" ability. Yeah, yeah, yeah..I know. He's a senior and deserves to play and what he's done for Auburn and how he's a double-tough competitor blah, blah, freakin' blah.
It's a given in this new offense. The QB has to have some ability to run. Cox can't. So I think you're right in saying Cox would run mostly the old offense and Burns or Field would get some reps in TF's offense.