KW turns 60 years old this year. He is on contract with the U of U through the 2023 season (at which time he will be 64). Last year, a 64 year old coach would have been the 7th oldest coach in CFB.
I am going to assume that, barring any scandals, KW will not be fired from the U of U. (Even if it is a "retirement" to avoid being fired). LaVell retired at 70. Bobby Bowden was 80 at retirement.
For more reference, here is a list of old fogies coaching college football. Four of them were 60 years old last year.