There is absolutely no way that a hard-nosed, strong willed coach is going to come in here and be either effective or successful. Jerry Jones is going to undermine anyone that comes in here and tries to strong arm him. That essentially rules out any NFL coaches with winning records and experience. That leads me to believe it is going to have to be someone from the college ranks.
When you start dipping into college, a lot more options become available, including the one I believe has the best chance for success with the current hierarchy in Dallas.
That's why I believe this team needs to go hard and fast after Briles, Sumlin or Shaw. We need to get someone in the office who has proven track record and success on one side of the ball. College coaches, for the most part, are used to more meddling from the NCAA and AD's. They have to go about their business with big brother constantly looking over their shoulder.
So, all that said, my dream scenario would be...
Shaw as HC and OC with Marinelli promoted to DC. With this couple we get hard nosed, intelligent aggressive play on both sides of the ball. They are also both guys with a track record of taking players and coaching them up--something this team is going to need given the lack of talent and salary cap issues.