First of all, KF needs to stay as HC. The main reason to fire a head football coach is because they no longer have control of their program. When you see players giving up at the end of the season, or severe discipline problems like what is happening at MSU, or major dysfunction within the program that is usually seen in public between coaches, players, administration, etc. then you fire the coach. But none of that is happening here. This team may not have the results they want but it isn't for a lack of cohesion. As a bonus, it really looks like recruiting is as good as it ever has been.
Second, you have to question what coach would want to step into this program after a coach like KF got run out of town. Any good coach wants to be able to come in and put their stamp on the program, make it their own, and it is much much easier to resurrect a dumpster fire than it is to keep a well-oiled machine running. When a coach gets hired at a dumpster fire, they get the authority to clean house as well as having a long-term commitment from the university because they know they are starting over. Iowa is not a dumpster fire by any stretch of the imagination and any coach that comes here would have the shadow of KF looming over them. Like when BB went to Illinois, or Alvarez to Wisconsin, or Leipold to Kansas, hell, they all just wanted to win a game. Any past success, if they ever had any was long gone. Then the goal is to get to a bowl game. Any bowl game would do, doesn't matter what toilet bowl it is. Anything after that is a bonus really. But these coaches came into programs that were so down that they could mold them however they wanted. With the portal now this can happen much faster and we are seeing that with BB. But any coach coming into Iowa knows that the expectations are much much higher than that from the get go. There aren't many coaches that want to step into KF's shoes with those expectations.