If you are a public school teacher and coach, just go. Chance are the principal really likes that you run a good program, but they dont really care. They will hire anyone that comes along to fill the position, maybe some guy that's only done a few 5ks, but he's "a runner" and that's good enough.
Staying because of a legacy is an excuse fueled by your own ego. Just go. Leave on your terms before they ask you to leave.