From someone who has coached at the collegiate level, albeit a different sport....
Loyalty, in my sport, used to be the way you got your opportunity to move up, grab more responsibility and ultimately get your shot to run your own show.
The coaching profession at the collegiate level in any sport has become a dog eat dog world. For those guys, a difference in title or job is hundreds of thousands of dollars. At the lower levels where you sometimes have to choose between food or rent for the month, the ability to jump can amount to the ability to add an extra couple hundred dollars and help yourself to not fall behind on student loans, car payments, etc.
May have given you a long winded explanation, but in my opinion the short answer anymore is no, loyalty is slowly dissipating. Anymore, at least in my sport, the coaches who tweet the most and self promote with videos, camps, etc seem to be the ones who move on and get opportunity