I think he will leave on his own, even for a lesser program or position if he gets 9 wins or more. I think he will be forced out with 8 wins or less although, I am a bit scared by the 8 win scenario. I think part of the reason the new coaches were brought in was to solidify the program when Kelly leaves. The coaches will have more incentive to work hard and stick around if they have the 1 year cushion. A main reason programs suffer during a coaching change is the assistants stop working and start looking. The other reason for the complete turnover would be so the AD could fire Kelly and justify it by telling his bosses he gave Kelly everything he needed to win but still couldn't. He will have one less year of buyout which would cover the cost of the extra year the assistants received(or part of it). If none of those are good enough, the AD may be forced to fire him to save his own job or may get fired himself.
Of course, I am not an Alum and have no inside information. I am just expressing my opinion.