It would be a mistake to view Kelly as a guy with AN offensive system and that's that. Kelly and BB have talked offensive football since he was coaching at UNH. I would assume they've gone over a lot broader ground than one simple idea.
I wouldn't be surprised to see Bill hire Chip as an consultant during the playoff run, and if it works out, bring him back as a coach/consultant, etc. Espeically if Josh moves on. Whatever he does here, he'd do it within the sructure of language and fundamentals that have been long established. As to the next OC, I think Brian Daboll has the first leg up.
BTW- Pepper Johnson just got fired. Any chance for him to come home?