I think Allen / Reggie want to stick with the west-coast / zone-blocking offense. Marty Mornhinweg / Chan Gailey would both be excellent choices to come in and coach this team.
For all of the talk about the 'vertical' passing game in Oakland, the Raiders have been running some kind of west-coast offense for the past decade. Mike White, Jon Gruden, Bill Callahan, Lane Kiffin, Tom Cable - that's the better part of the past fifteen years, all of them running a west coast offensive system.
I wouldn't mind seeing Norv Turner return to bring back the vertical system. It's highly unlikely, however.