Oleary doesn't need to do anything right now. I wouldn't want him to announce until new AD is in place. announce then, the AD can start with a fresh plate. The team doesn't need him quitting on them now. They are not good but are still playing hard.
Here's what a legend with class says at retirement at age 69: "This is my school, my alma mater. I love it and I love my players. But in my opinion, they deserved better coaching than they have been getting from me this year." - Bear Bryant.