I think it's a little weird Bama didn't seem interested in keeping him.
Just getting back from a four-week vacation (Utah Nat'l Parks in the offseason!!) and am slow on the uptake, but if you are implying this could be similar to the Nussmeier hire (...) maybe (...) because always maybe. But the situations aren't very similar.
For one, Harbaugh, not Hoke, made the hire and he has been a great hirer of coaching talent**. For two, whereas Alabama fans were cheering Nuss out the door, they are clearly disappointed about losing Gattis. And in the neutral-but-different-than-Nuss category, Gattis hasn't ever been an OC. That last one remains a legitimate question/concern/curiosity, but in his last two stops, he's been part of two "highest end" offenses, likely absorbed plenty, and is a fast rider for other reasons. I.E., no one is questioning his recruiting or WR chops.
**(this one is worth spending an extra second on, however, since both of Harbaugh's failed hires - Drevno and Pep - have been OCs. Skepticism is healthy. However, both of those were lapdog hires, whereas Gattis is the first Harbaugh OC to be reported to take over play calling. Maybe that doesn't qualify as a paradigm shift, but it is an extra reason for positivity.)