Sounds smart to me , he is only what,31?, works with a winning team, can still learn a ton of things before moving on. He is young and will surely go places... I think this patience will benefit him in the long run.
Strictly from a financial perspective, his value goes up if he stays on board and gets a ring or two as an offensive coordinator. There will be vacancies each year, he's still a young man and most certainly has a job as a head coach waiting for him in the future.
If some of these unproven coaches from college come over, get paid $25 million for 4 or 5 years, you know McDaniels will get his when he leaves the nest.