Bill's retirement date this time around won't have anything to do with the shame of losing, in my opinion.
With Currie apparently conducting himself like some sort of feces throwing baboon at these recurring AD job interviews, it would seem that half of Bill's purpose in life, namely to outlast Currie and somehow convince the next AD to allow Sean to takeover, is in jeopardy. I suspect Bill has started to accept that he won't outlast Currie.
The other half of Bill's purpose, the 200th win, will take another year. Which is very achievable. So, I expect him to stay another year.
Will the 200th be enough to satisfy Bill? I really don't know.