I've thought Shanahan for a while now. Even more so lately.
Jerry believes things start with the QB. He doesn't want to mess up and not have a strong figure to guide Romo (and that Tony will respect, a la Big Bill). The current arrangement with Garrett was a hopeful one, but it hasn't worked.
Jerry will want a guy who wants to be a coach, not a GM. That rules out Holmgren.
Jerry likes stars and flashiness. That rules out Cowher, in addition to the fact that Dallas is not in North Carolina.
Heard Francesa over the weekend thinking the same thing regarding the personalities.
That said, Jerry has always been unpredictable... every single time, from Jerry to Wade. I think this time he'll be fighting with himself over 1) a big name and proven winner for his big stadium, and 2) not wanting to take any steps back.
In the end, his frustration will lead him to his default mode -- go big, go proven. And Shanahan will be the biggest name that he can work with.