Would be compelling to watch if Auburn showed real interest.
If Gill stays at Buffalo, he would more than likely become their "Bobfather." But coaching in a BCS conf. at a name school like Auburn would be hard to turn down. It might depend on how much he wants to stick around his current AD and if he wants to try and build that program over the long haul. And, if he wants to put himself in a situation where the pressure is on to win immediately.
He'll be successful anywhere he goes. I'm sure he's still got one eye on NU. But of course, that depends on how long Bo stays around.
When TO's successor for AD takes office and Bo leaves for some reason (I hope he stays) then Gill's time becomes right to coach at NU (after Frank, idiot AD; after BC, too close of a relationship with TO and maybe not ready to meet the immediate need).
And BCS conference experience would be nice for Gill to have before he were to come back here.