Truer words have never been spoken.  

I believe that there is a video from a couple of years ago at Jeb's retirement as governor:  Bush 41 is speaking at his son's departure, and he starts to tear up about this exact thing.  He knew that the "Bush" brand was dead.  Jeb was supposed to be the heir apparent.

GHWB knew in 2006, how much his son had fucked up his presidency, and also knew that Jeb's future as a politician was also over as a result.