I disagree. The worst case scenario basically involves what you are saying. For example, lets say the following happens
We hire Key, keep the defensive staff, and bring in a new offensive staff. However, the offense still struggles as it has the past 4 years, and the defense regresses to the mean with respects to turnovers and has some key losses to being back to closer to what it was the past 3 years (and what we have seen against better teams this year at times), and we go back to being a 3-9 team. Then we are the laughing stock who decided to fire a coach and AD mid year just to keep most of the staff and still get terrible results.
I really do not understand the love for Key. Pitt was a great game. Beyond the change at kickers, which I'm not sure we wouldn't have done anyways as it wasn't like the old kicker was entrenched as a multi year starter, I doubt it had much to do with anything he did during the 4 days after Collins got fired and was more just to general relief of not being under the cloud of a coach about to be fired. Since then we've had a mediocre showing against Duke and then three bad performances coming off a bye week. You would expect that we'd continue to improve as more time has gone away but we haven't.
Trying to say the wheels are going to come off for Key next year is pure conjecture. Just like saying Key will win 8-10 games next season is pure conjecture. We can say that about ANY candidate we hire. There are zero guarantees for anyone. Scott Frost was as about the most perfect hire for any situation as there has been...and he completely crapped the bed at Nebraska.
What's the point here? The point is to WIN. Period. This isn't a beauty contest. We already had a coach that tried to make this a beauty contest and he just got fired. I've said REPEATEDLY that to even be considered for the job Key would need to go 6-2 in his 8 game "tryout". That means he would have proven himself in a crucible of salvaging a disaster of a season, at one of the hardest jobs in P5. He literally would have won at GT, and under extreme circumstances. Isn't that the point? Who can you say that about with other candidates? Not. A. Single. One. None of them...even the popular Jamey Chadwell, the seasoned Bill O'Brien, or even popular Deion Sanders. Key will be the only one that can say he won at GT and have an actual record of doing that.
You keep bringing up "Key was part of the problem" without acknowledging the fact that Collins was meddling with how coaches were coaching, and our coaches had one arm tied behind their backs. There's a reason why players kept tweeting out that coaches fired last year were "scape goats". Coaches have said that Collins wouldn't allow the staff to do certain things (practice 1v1s, not always practicing full speed, not preparing backups to play in case of emergency scenarios - see Pyron, etc). If you can't acknowledge that our coaches were being limited, than you probably have never worked a day in your life. AT some point, regardless of how good you are at your job, if your boss limits the tools you're allowed to use, you're not going to be successful. The fact that Key has been able to win as many games in 5 attempts than Geoff Collins has won each of the last 3 full seasons tells us Key can coach...despite however much you're trying to diminish that.
The worst case scenario isn't keeping Key. The worst case scenario would be paying a boat load of money for a new coach and staff and watching them fail. That would be TWO coaches failing back to back and sending GT further into debt.