Harbaugh has been cryptic recently about his future with San Francisco, but by all indications he will not be returning for the final year of his contract in 2015. He's been connected with the Michigan job since before Brady Hoke was fired, and if he wanted to leave to take over the Wolverines, the 49ers would reportedly not ask for any compensation to let him out of his contract early.
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If he were to leave for another NFL job, however, the 49ers would supposedly ask for "a king's ransom" in exchange for releasing him, as the potential for embarrassment is much higher if Harbaugh remains in the NFL, especially if it's with the Oakland Raiders. ESPN's Adam Schefter reported that Harbaugh is supposedly leaning more towards leaving for Michigan, but nothing will happen until next week when San Francisco's season ends.