I have three doubts about this.
1. If there is any chance that the Michigan job might be available after this season, he will at least pass on us (already discussed ad nauseam, i know)
2. While there are folks who complained about his salary being upped, yes. But there are also a ton of rich influential Stanford alums who are really pumped about Stanford football because of him. Nobody has really seen the full power of the Stanford athletic boosters when it comes to football. If they ever get it in their heads that football is more important than their seemingly dozens of other amazing athletic programs, Harbaugh wouldn't dare go anywhere else.
3. By the time we are able to talk to Harbaugh, there will certainly be some other job openings at other schools, and those could potentially outbid us. Just a thought, but if JoePa retires, and PSU decides (unlikely as it seems) they want him.... what (other than Michigan) could possibly stop him from going there?