Seems strange that Harbaugh would leave now after finally having some success (unless he was just trying to rescue his image before bolting). 

I also am not sure how you can have a source simply say that he "might be tempted." What does that even mean? Unless he said "I might be tempted," I'm not sure that speculation warrants a story.

And... a lot of this seems to be on a similar plane of Day going to the Bears.

That said, it's being reported. 

Sources from both from the NFL side, and at Michigan, tell The Athletic that Jim Harbaugh might be tempted to leave the Wolverines to return to the NFL: https://t.co/BvGNjBZmdv
— Bruce Feldman (@BruceFeldmanCFB) January 4, 2022