IMO, Bill O'Brien would be a lot like George O'Leary. Absolute hard@ss of a coach, he would get us back to regular bowl games, win 9-11 games every few seasons, and we would be play good fundamental football on both sides. His hard@ss schtick doesn't play well with NFL players making more money than him, but in college it works. In his six full seasons for the Texans (he was fired 4 games into the 7th season), he finished first in the division four times. Bonus: he would have learned Saban's structure for a college football program and could implement some of it at GT (minus probably the bagmen). At Penn State, he finished 2nd and 3rd in the division with a decimated roster due to the Joe Paterno scandal. He'll develop players to be NFL draft picks, and QBs would line up to play for him. This guy can coach QBs...there's a reason why Bill Belichek wanted him to coach in New England.
Given GT's current predicament, and how many programs will be looking for a coach, GT could do a LOT worse than Bill O'Brien.