These are my thoughts as well. I don't see him leaving until there is something
better for him here in the state (aka HC at either Utah or BYU) ...unless Georgia DC or Texas DC or some crazy scenario presents itself that would pay him $2-5M/yr as a coordinator.
He's getting ~$1M as DC at BYU and I'm sure if things keep going the way they are, BYU will be happy to match a Scalleywag type DC salary (Scalley makes $1.33M this year) to keep him.
That said, IF Hill leaves, we have a lot of good coaches on his staff that are learning his style and intensity and I think they are all like minded. I could see a Poppinga or Ena take over for Hill and have a similar system and do well.
...but I want Hill to stay around as long as possible