All the guys that have run well at that age are East-African. Off of the top of my head, Carlos Lopes is the exception. Shorter, Ritz and Rodgers got nowhere close to running well at that age.
Look up Jack Foster. By the standards of his time he ran exceptionally well as an older athlete. Also look up another NZ runner, John Campbell.
So maybe Rupp has a 1% chance of not slowing down at age 37?
I understood what you want to say. You are also correct -- it is not "this statement above" that requires me to "wait and see". For example, I not only want to know "if" but "if so, how much?"