Caserio doesn't have final say now. If he's offered a position where he has final say on personnel, it's considered a promotion and thus no compensation is required.
I'm not sure who Caserio's heir is; considering that he interviewed two years ago for a few positions (Dolphins being one I recall), I figure there is a succession plan in place, I just don't know who. For McDaniels the prevailing story is that Brian Daboll would be the successor, even if not explicitly given the title immediately (although since he does have past OC experience, I'd be surprised if he didn't get the title and full responsibility).