Hopefully he doesn't make the same mistake that the last AD made, which was to try and completely overhaul the existing offense. Anybody that steps in as AD should be looking to find a coach that can transition successfully with the players that have already committed to the university. The good thing about Callahan is that he has the athletes to run AND pass, but they just need some f'ing direction for once.
And would everybody stop talking about bringing in somebody from the "brotherhood" or whatever the f#*k? The new AD needs to first assess the situation with Callahan, and then make sure he has or is going to hire the BEST COACH AVAILABLE. Would you honestly take Turner Gill over somebody like Jeff Tedford, Greg Schiano, or anybody else that has proven himself to be capable of coaching a major college program?
And even if Osborne steps in as interim AD, who says he's firing anybody? I think he would leave that up to whoever is directly taking over at AD, and thus having to work with the next HC. I think Callahan may very well be the head coach next year, albeit with a different looking group of assistants. Even Callahan has got to recognize by now that his job security is directly linked to Kevin Cosgrove's defense. However, I think Osborne would recognize that his job is not to make decisions for the next guy in line, but to basically handle damage control in the interim.