All things considered, I've got to believe the only way Romo would make a return to football is if Dak went down injured. Even then, it would be doubtful that the FO would allow that to happen. The chances for creating team dissention in the long run would be great.
Additionally, replacing another QB with a team other than the Cowboys would entail learning a totally strange system with unfamiliar players. That would not be a very promising formula for finding success. I think Tony's exodus to broadcasting is a make-it-or-break-it proposition, although his pleasant personality should stand him in good stead.